feat: add weekly contest 382

solution/3000-3099/3019.Number of Changing Keys/README.md

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+# [3019. 按键变更的次数](https://leetcode.cn/problems/number-of-changing-keys)
+
+[English Version](/solution/3000-3099/3019.Number%20of%20Changing%20Keys/README_EN.md)
+
+## 题目描述
+
+<!-- 这里写题目描述 -->
+
+<p>给你一个下标从<strong> 0</strong> 开始的字符串 <code>s</code> ，该字符串由用户输入。按键变更的定义是：使用与上次使用的按键不同的键。例如 <code>s = "ab"</code> 表示按键变更一次，而 <code>s = "bBBb"</code> 不存在按键变更。</p>
+
+<p>返回用户输入过程中按键变更的次数。</p>
+
+<p><strong>注意：</strong><code>shift</code> 或 <code>caps lock</code> 等修饰键不计入按键变更，也就是说，如果用户先输入字母 <code>'a'</code> 然后输入字母 <code>'A'</code> ，不算作按键变更。</p>
+
+<p>&nbsp;</p>
+
+<p><strong class="example">示例 1：</strong></p>
+
+<pre>
+<strong>输入：</strong>s = "aAbBcC"
+<strong>输出：</strong>2
+<strong>解释：</strong> 
+从 s[0] = 'a' 到 s[1] = 'A'，不存在按键变更，因为不计入 caps lock 或 shift 。
+从 s[1] = 'A' 到 s[2] = 'b'，按键变更。
+从 s[2] = 'b' 到 s[3] = 'B'，不存在按键变更，因为不计入 caps lock 或 shift 。
+从 s[3] = 'B' 到 s[4] = 'c'，按键变更。
+从 s[4] = 'c' 到 s[5] = 'C'，不存在按键变更，因为不计入 caps lock 或 shift 。
+</pre>
+
+<p><strong class="example">示例 2：</strong></p>
+
+<pre>
+<strong>输入：</strong>s = "AaAaAaaA"
+<strong>输出：</strong>0
+<strong>解释：</strong> 不存在按键变更，因为这个过程中只按下字母 'a' 和 'A' ，不需要进行按键变更。<!-- notionvc: 8849fe75-f31e-41dc-a2e0-b7d33d8427d2 -->
+</pre>
+
+<p>&nbsp;</p>
+
+<p><strong>提示：</strong></p>
+
+<ul>
+	<li><code>1 &lt;= s.length &lt;= 100</code></li>
+	<li><code>s</code> 仅由英文大写字母和小写字母组成。</li>
+</ul>
+
+## 解法
+
+### 方法一
+
+<!-- tabs:start -->
+
+```python
+
+```
+
+```java
+
+```
+
+```cpp
+
+```
+
+```go
+
+```
+
+<!-- tabs:end -->
+
+<!-- end -->

solution/3000-3099/3019.Number of Changing Keys/README_EN.md

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+# [3019. Number of Changing Keys](https://leetcode.com/problems/number-of-changing-keys)
+
+[中文文档](/solution/3000-3099/3019.Number%20of%20Changing%20Keys/README.md)
+
+## Description
+
+<p>You are given a <strong>0-indexed </strong>string <code>s</code> typed by a user. Changing a key is defined as using a key different from the last used key. For example, <code>s = &quot;ab&quot;</code> has a change of a key while <code>s = &quot;bBBb&quot;</code> does not have any.</p>
+
+<p>Return <em>the number of times the user had to change the key. </em></p>
+
+<p><strong>Note: </strong>Modifiers like <code>shift</code> or <code>caps lock</code> won&#39;t be counted in changing the key that is if a user typed the letter <code>&#39;a&#39;</code> and then the letter <code>&#39;A&#39;</code> then it will not be considered as a changing of key.</p>
+
+<p>&nbsp;</p>
+<p><strong class="example">Example 1:</strong></p>
+
+<pre>
+<strong>Input:</strong> s = &quot;aAbBcC&quot;
+<strong>Output:</strong> 2
+<strong>Explanation:</strong> 
+From s[0] = &#39;a&#39; to s[1] = &#39;A&#39;, there is no change of key as caps lock or shift is not counted.
+From s[1] = &#39;A&#39; to s[2] = &#39;b&#39;, there is a change of key.
+From s[2] = &#39;b&#39; to s[3] = &#39;B&#39;, there is no change of key as caps lock or shift is not counted.
+From s[3] = &#39;B&#39; to s[4] = &#39;c&#39;, there is a change of key.
+From s[4] = &#39;c&#39; to s[5] = &#39;C&#39;, there is no change of key as caps lock or shift is not counted.
+
+</pre>
+
+<p><strong class="example">Example 2:</strong></p>
+
+<pre>
+<strong>Input:</strong> s = &quot;AaAaAaaA&quot;
+<strong>Output:</strong> 0
+<strong>Explanation:</strong> There is no change of key since only the letters &#39;a&#39; and &#39;A&#39; are<!-- notionvc: 8849fe75-f31e-41dc-a2e0-b7d33d8427d2 --> pressed which does not require change of key.
+</pre>
+
+<p>&nbsp;</p>
+<p><strong>Constraints:</strong></p>
+
+<ul>
+	<li><code>1 &lt;= s.length &lt;= 100</code></li>
+	<li><code>s</code> consists of only upper case and lower case English letters.</li>
+</ul>
+
+## Solutions
+
+### Solution 1
+
+<!-- tabs:start -->
+
+```python
+
+```
+
+```java
+
+```
+
+```cpp
+
+```
+
+```go
+
+```
+
+<!-- tabs:end -->
+
+<!-- end -->

solution/3000-3099/3020.Find the Maximum Number of Elements in Subset/README.md

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+# [3020. 子集中元素的最大数量](https://leetcode.cn/problems/find-the-maximum-number-of-elements-in-subset)
+
+[English Version](/solution/3000-3099/3020.Find%20the%20Maximum%20Number%20of%20Elements%20in%20Subset/README_EN.md)
+
+## 题目描述
+
+<!-- 这里写题目描述 -->
+
+<p>给你一个<strong> 正整数 </strong>数组 <code>nums</code> 。</p>
+
+<p>你需要从数组中选出一个满足下述条件的<span data-keyword="subset">子集</span>：</p>
+
+<ul>
+	<li>你可以将选中的元素放置在一个下标从 <strong>0</strong> 开始的数组中，并使其遵循以下模式：<code>[x, x<sup>2</sup>, x<sup>4</sup>, ..., x<sup>k/2</sup>, x<sup>k</sup>, x<sup>k/2</sup>, ..., x<sup>4</sup>, x<sup>2</sup>, x]</code>（<strong>注意</strong>，<code>k</code> 可以是任何 <strong>非负</strong> 的 2 的幂）。例如，<code>[2, 4, 16, 4, 2]</code> 和 <code>[3, 9, 3]</code> 都符合这一模式，而 <code>[2, 4, 8, 4, 2]</code> 则不符合。</li>
+</ul>
+
+<p>返回满足这些条件的子集中，元素数量的 <strong>最大值 </strong><em>。</em></p>
+
+<p>&nbsp;</p>
+
+<p><strong class="example">示例 1：</strong></p>
+
+<pre>
+<strong>输入：</strong>nums = [5,4,1,2,2]
+<strong>输出：</strong>3
+<strong>解释：</strong>选择子集 {4,2,2} ，将其放在数组 [2,4,2] 中，它遵循该模式，且 2<sup>2</sup> == 4 。因此答案是 3 。
+</pre>
+
+<p><strong class="example">示例 2：</strong></p>
+
+<pre>
+<strong>输入：</strong>nums = [1,3,2,4]
+<strong>输出：</strong>1
+<strong>解释：</strong>选择子集 {1}，将其放在数组 [1] 中，它遵循该模式。因此答案是 1 。注意我们也可以选择子集 {2} 、{4} 或 {3} ，可能存在多个子集都能得到相同的答案。
+</pre>
+
+<p>&nbsp;</p>
+
+<p><strong>提示：</strong></p>
+
+<ul>
+	<li><code>2 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
+	<li><code>1 &lt;= nums[i] &lt;= 10<sup>9</sup></code></li>
+</ul>
+
+## 解法
+
+### 方法一
+
+<!-- tabs:start -->
+
+```python
+
+```
+
+```java
+
+```
+
+```cpp
+
+```
+
+```go
+
+```
+
+<!-- tabs:end -->
+
+<!-- end -->

solution/3000-3099/3020.Find the Maximum Number of Elements in Subset/README_EN.md

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+# [3020. Find the Maximum Number of Elements in Subset](https://leetcode.com/problems/find-the-maximum-number-of-elements-in-subset)
+
+[中文文档](/solution/3000-3099/3020.Find%20the%20Maximum%20Number%20of%20Elements%20in%20Subset/README.md)
+
+## Description
+
+<p>You are given an array of <strong>positive</strong> integers <code>nums</code>.</p>
+
+<p>You need to select a <span data-keyword="subset">subset</span> of <code>nums</code> which satisfies the following condition:</p>
+
+<ul>
+	<li>You can place the selected elements in a <strong>0-indexed</strong> array such that it follows the pattern: <code>[x, x<sup>2</sup>, x<sup>4</sup>, ..., x<sup>k/2</sup>, x<sup>k</sup>, x<sup>k/2</sup>, ..., x<sup>4</sup>, x<sup>2</sup>, x]</code> (<strong>Note</strong> that <code>k</code> can be be any <strong>non-negative</strong> power of <code>2</code>). For example, <code>[2, 4, 16, 4, 2]</code> and <code>[3, 9, 3]</code> follow the pattern while <code>[2, 4, 8, 4, 2]</code> does not.</li>
+</ul>
+
+<p>Return <em>the <strong>maximum</strong> number of elements in a subset that satisfies these conditions.</em></p>
+
+<p>&nbsp;</p>
+<p><strong class="example">Example 1:</strong></p>
+
+<pre>
+<strong>Input:</strong> nums = [5,4,1,2,2]
+<strong>Output:</strong> 3
+<strong>Explanation:</strong> We can select the subset {4,2,2}, which can be placed in the array as [2,4,2] which follows the pattern and 2<sup>2</sup> == 4. Hence the answer is 3.
+</pre>
+
+<p><strong class="example">Example 2:</strong></p>
+
+<pre>
+<strong>Input:</strong> nums = [1,3,2,4]
+<strong>Output:</strong> 1
+<strong>Explanation:</strong> We can select the subset {1}, which can be placed in the array as [1] which follows the pattern. Hence the answer is 1. Note that we could have also selected the subsets {2}, {4}, or {3}, there may be multiple subsets which provide the same answer. 
+</pre>
+
+<p>&nbsp;</p>
+<p><strong>Constraints:</strong></p>
+
+<ul>
+	<li><code>2 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
+	<li><code>1 &lt;= nums[i] &lt;= 10<sup>9</sup></code></li>
+</ul>
+
+## Solutions
+
+### Solution 1
+
+<!-- tabs:start -->
+
+```python
+
+```
+
+```java
+
+```
+
+```cpp
+
+```
+
+```go
+
+```
+
+<!-- tabs:end -->
+
+<!-- end -->

solution/3000-3099/3021.Alice and Bob Playing Flower Game/README.md

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+# [3021. Alice 和 Bob 玩鲜花游戏](https://leetcode.cn/problems/alice-and-bob-playing-flower-game)
+
+[English Version](/solution/3000-3099/3021.Alice%20and%20Bob%20Playing%20Flower%20Game/README_EN.md)
+
+## 题目描述
+
+<!-- 这里写题目描述 -->
+
+<p>Alice 和 Bob 在一个长满鲜花的环形草地玩一个回合制游戏。环形的草地上有一些鲜花，Alice 到&nbsp;Bob 之间顺时针有 <code>x</code>&nbsp;朵鲜花，逆时针有 <code>y</code>&nbsp;朵鲜花。</p>
+
+<p>游戏过程如下：</p>
+
+<ol>
+	<li>Alice 先行动。</li>
+	<li>每一次行动中，当前玩家必须选择顺时针或者逆时针，然后在这个方向上摘一朵鲜花。</li>
+	<li>一次行动结束后，如果所有鲜花都被摘完了，那么 <strong>当前</strong>&nbsp;玩家抓住对手并赢得游戏的胜利。</li>
+</ol>
+
+<p>给你两个整数&nbsp;<code>n</code>&nbsp;和&nbsp;<code>m</code>&nbsp;，你的任务是求出满足以下条件的所有&nbsp;<code>(x, y)</code>&nbsp;对：</p>
+
+<ul>
+	<li>按照上述规则，Alice 必须赢得游戏。</li>
+	<li>Alice 顺时针方向上的鲜花数目&nbsp;<code>x</code>&nbsp;必须在区间&nbsp;<code>[1,n]</code>&nbsp;之间。</li>
+	<li>Alice 逆时针方向上的鲜花数目 <code>y</code>&nbsp;必须在区间&nbsp;<code>[1,m]</code>&nbsp;之间。</li>
+</ul>
+
+<p>请你返回满足题目描述的数对&nbsp;<code>(x, y)</code>&nbsp;的数目。</p>
+
+<p>&nbsp;</p>
+
+<p><strong class="example">示例 1：</strong></p>
+
+<pre>
+<b>输入：</b>n = 3, m = 2
+<b>输出：</b>3
+<b>解释：</b>以下数对满足题目要求：(1,2) ，(3,2) ，(2,1) 。
+</pre>
+
+<p><strong class="example">示例 2：</strong></p>
+
+<pre>
+<b>输入：</b>n = 1, m = 1
+<b>输出：</b>0
+<b>解释：</b>没有数对满足题目要求。
+</pre>
+
+<p>&nbsp;</p>
+
+<p><strong>提示：</strong></p>
+
+<ul>
+	<li><code>1 &lt;= n, m &lt;= 10<sup>5</sup></code></li>
+</ul>
+
+## 解法
+
+### 方法一
+
+<!-- tabs:start -->
+
+```python
+
+```
+
+```java
+
+```
+
+```cpp
+
+```
+
+```go
+
+```
+
+<!-- tabs:end -->
+
+<!-- end -->