docs: 新增No268题解

Author: Mayandev

leetcode刷题/README.md

@@ -1,48 +1,49 @@
 # LootCode 刷题
 
-- [No.1 两数之和](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No1_two-sum.md)
-- [No.7 整数反转](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No7_reverse.md)
-- [No.8 字符串转换整数 (atoi)](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No8_my-atoi.md)
+- [No.1 两数之和](note/No1_two-sum.md)
+- [No.7 整数反转](note/No7_reverse.md)
+- [No.8 字符串转换整数 (atoi)](note/No8_my-atoi.md)
 - [No.13 罗马数字转整数](note/No13_roman-to-int.md)
-- [No.14 最长公共前缀](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No14_longest-common-prefix.md)
-- [No.19 删除链表倒数第 n 个节点](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No19_remove-nth-from-end.md)
-- [No.20 有效的括号](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No20_is-valid.md)
-- [No.21 合并两个有序链表](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No21_merge-two-lists.md)
-- [No.26 从排序数组中删除重复项](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No26_remove-duplicates.md)
-- [No.36 有效的数独](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No36_isvalid-sudoku.md)
-- [No.38 报数](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No38_count-and-say.md)
-- [No.48 旋转图像](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No48_rotate.md)
+- [No.14 最长公共前缀](note/No14_longest-common-prefix.md)
+- [No.19 删除链表倒数第 n 个节点](note/No19_remove-nth-from-end.md)
+- [No.20 有效的括号](note/No20_is-valid.md)
+- [No.21 合并两个有序链表](note/No21_merge-two-lists.md)
+- [No.26 从排序数组中删除重复项](note/No26_remove-duplicates.md)
+- [No.36 有效的数独](note/No36_isvalid-sudoku.md)
+- [No.38 报数](note/No38_count-and-say.md)
+- [No.48 旋转图像](note/No48_rotate.md)
 - [No.53 最大子序和](note/No53_max-sub-array.md)
-- [No.66 加一](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No66_plus-one.md)
-- [No.70 爬楼梯](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No70_climb-stairs.md)
-- [No.88 合并两个有序数组](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No88_merge.md)
-- [No.98 验证二叉搜索树](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No98_is-valid-BST.md)
-- [No.104 二叉树的最大深度](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No104_max-depth.md)
-- [No.121 买卖股票的最佳时机](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No121_max-profit.md)
-- [No.122 买卖股票的最佳时机 II](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No122_max-profit.md)
-- [No.125 验证回文串](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No125_is-palindrome.md)
-- [No.136 只出现一次的数字](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No136_single-number.md)
-- [No.141 环形链表](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No141_has_cycle.md)
-- [No.155 最小栈](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No155_min-stack.md)
-- [No.160 相交链表](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No160_get-intersection-node.md)
-- [No.169 多数元素](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No169_majority-element.md)
-- [No.189 旋转数组](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No189_rotate-arr.md)
+- [No.66 加一](note/No66_plus-one.md)
+- [No.70 爬楼梯](note/No70_climb-stairs.md)
+- [No.88 合并两个有序数组](note/No88_merge.md)
+- [No.98 验证二叉搜索树](note/No98_is-valid-BST.md)
+- [No.104 二叉树的最大深度](note/No104_max-depth.md)
+- [No.121 买卖股票的最佳时机](note/No121_max-profit.md)
+- [No.122 买卖股票的最佳时机 II](note/No122_max-profit.md)
+- [No.125 验证回文串](note/No125_is-palindrome.md)
+- [No.136 只出现一次的数字](note/No136_single-number.md)
+- [No.141 环形链表](note/No141_has_cycle.md)
+- [No.155 最小栈](note/No155_min-stack.md)
+- [No.160 相交链表](note/No160_get-intersection-node.md)
+- [No.169 多数元素](note/No169_majority-element.md)
+- [No.189 旋转数组](note/No189_rotate-arr.md)
 - [No.191 位1的个数](note/No191_hamming-weight.md)
-- [No.198 打家劫舍](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No198_rob.md)
-- [No.204 计数质数](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No204_count-primes.md)
-- [No.206 反转链表](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No206_reverse-list.md)
-- [No.234 回文链表](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No234_is-palindrome.md)
-- [No.237 删除链表节点](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No237_delete-node.md)
-- [No.242 有效的字母异位词](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No242_is-anagram.md)
-- [No.283 移动零](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No283_move-zeroes.md)
-- [No.326 3的幂](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No326_is-power-of-three.md)
-- [No.350 两个数组的交集 II](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No350_intersect.md)
+- [No.198 打家劫舍](note/No198_rob.md)
+- [No.204 计数质数](note/No204_count-primes.md)
+- [No.206 反转链表](note/No206_reverse-list.md)
+- [No.234 回文链表](note/No234_is-palindrome.md)
+- [No.237 删除链表节点](note/No237_delete-node.md)
+- [No.242 有效的字母异位词](note/No242_is-anagram.md)
+- [No.268 缺失的数字](note/No268_missing-number.md)
+- [No.283 移动零](note/No283_move-zeroes.md)
+- [No.326 3的幂](note/No326_is-power-of-three.md)
+- [No.350 两个数组的交集 II](note/No350_intersect.md)
 - [No.384 打乱数组](note/No384_shuffle.md)
-- [No.387 字符串中的第一个唯一字符](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No387_first-uniq-char.md)
-- [No.412 Fizz Buzz](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No412_fizz-buzz.md)
-- [No.448 找到所有数组中消失的数字](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No448_find-disappeared-numbers.md)
-- [No.492 构造矩形](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No492_construct-rectangle.md)
-- [No.581 最短无序连续子数组](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No581_find-unsorted-subarray.md)
+- [No.387 字符串中的第一个唯一字符](note/No387_first-uniq-char.md)
+- [No.412 Fizz Buzz](note/No412_fizz-buzz.md)
+- [No.448 找到所有数组中消失的数字](note/No448_find-disappeared-numbers.md)
+- [No.492 构造矩形](note/No492_construct-rectangle.md)
+- [No.581 最短无序连续子数组](note/No581_find-unsorted-subarray.md)
 
 ## 分类
 
@@ -51,63 +52,63 @@
 #### 数组初级
 
 
-- [No.1 两数之和](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No1_two-sum.md)
-- [No.26 从排序数组中删除重复项](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No26_remove-duplicates.md)
-- [No.36 有效的数独](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No36_isvalid-sudoku.md)
-- [No.48 旋转图像](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No48_rotate.md)
-- [No.66 加一](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No66_plus-one.md)
-- [No.122 买卖股票的最佳时机 II](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No122_max-profit.md)
-- [No.136 只出现一次的数字](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No136_single-number.md)
-- [No.189 旋转数组](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No189_rotate-arr.md)
-- [No.283 移动零](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No283_move-zeroes.md)
-- [No.350 两个数组的交集 II](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No350_intersect.md)
-- [No.448 找到所有数组中消失的数字](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No448_find-disappeared-numbers.md)
-- [No.581 最短无序连续子数组](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No581_find-unsorted-subarray.md)
+- [No.1 两数之和](note/No1_two-sum.md)
+- [No.26 从排序数组中删除重复项](note/No26_remove-duplicates.md)
+- [No.36 有效的数独](note/No36_isvalid-sudoku.md)
+- [No.48 旋转图像](note/No48_rotate.md)
+- [No.66 加一](note/No66_plus-one.md)
+- [No.122 买卖股票的最佳时机 II](note/No122_max-profit.md)
+- [No.136 只出现一次的数字](note/No136_single-number.md)
+- [No.189 旋转数组](note/No189_rotate-arr.md)
+- [No.283 移动零](note/No283_move-zeroes.md)
+- [No.350 两个数组的交集 II](note/No350_intersect.md)
+- [No.448 找到所有数组中消失的数字](note/No448_find-disappeared-numbers.md)
+- [No.581 最短无序连续子数组](note/No581_find-unsorted-subarray.md)
 
 ### 字符串
 
 #### 字符串初级
 
-- [No.7 整数反转](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No7_reverse.md)
-- [No.8 字符串转换整数 (atoi)](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No8_my-atoi.md)
-- [No.14 最长公共前缀](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No14_longest-common-prefix.md)
-- [No.28 实现 strStr()](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No28_str-str.md)
-- [No.38 报数](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No38_count-and-say.md)
-- [No.125 验证回文串](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No125_is-palindrome.md)
-- [No.242 有效的字母异位词](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No242_is-anagram.md)
-- [No.387 字符串中的第一个唯一字符](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No387_first-uniq-char.md)
+- [No.7 整数反转](note/No7_reverse.md)
+- [No.8 字符串转换整数 (atoi)](note/No8_my-atoi.md)
+- [No.14 最长公共前缀](note/No14_longest-common-prefix.md)
+- [No.28 实现 strStr()](note/No28_str-str.md)
+- [No.38 报数](note/No38_count-and-say.md)
+- [No.125 验证回文串](note/No125_is-palindrome.md)
+- [No.242 有效的字母异位词](note/No242_is-anagram.md)
+- [No.387 字符串中的第一个唯一字符](note/No387_first-uniq-char.md)
 
 ### 链表
 
 #### 链表初级
 
-- [No.19 删除链表倒数第 n 个节点](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No19_remove-nth-from-end.md)
-- [No.21 合并两个有序链表](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No21_merge-two-lists.md)
-- [No.141 环形链表](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No141_has_cycle.md)
-- [No.206 反转链表](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No206_reverse-list.md)
-- [No.234 回文链表](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No234_is-palindrome.md)
-- [No.237 删除链表节点](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No237_delete-node.md)
+- [No.19 删除链表倒数第 n 个节点](note/No19_remove-nth-from-end.md)
+- [No.21 合并两个有序链表](note/No21_merge-two-lists.md)
+- [No.141 环形链表](note/No141_has_cycle.md)
+- [No.206 反转链表](note/No206_reverse-list.md)
+- [No.234 回文链表](note/No234_is-palindrome.md)
+- [No.237 删除链表节点](note/No237_delete-node.md)
 
 
 ### 数学
 
 #### 数学初级
 
 - [No.13 罗马数字转整数](note/No13_roman-to-int.md)
-- [No.326 3的幂](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No326_is-power-of-three.md)
-- [No.204 计数质数](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No204_count-primes.md)
-- [No.492 构造矩形](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No492_construct-rectangle.md)
+- [No.326 3的幂](note/No326_is-power-of-three.md)
+- [No.204 计数质数](note/No204_count-primes.md)
+- [No.492 构造矩形](note/No492_construct-rectangle.md)
 
 
 ### 动态规划
 
 - [No.53 最大子序和](note/No53_max-sub-array.md)
-- [No.70 爬楼梯](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No70_climb-stairs.md)
-- [No.121 买卖股票的最佳时机](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No121_max-profit.md)
-- [No.198 打家劫舍](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No198_rob.md)
+- [No.70 爬楼梯](note/No70_climb-stairs.md)
+- [No.121 买卖股票的最佳时机](note/No121_max-profit.md)
+- [No.198 打家劫舍](note/No198_rob.md)
 
 
 ### 排序和搜索
 
-- [No.88 合并两个有序数组](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No88_merge.md)
-- [No.278 第一个错误的版本](https://github.com/Mayandev/javascript_algorithm/blob/master/leetcode%E5%88%B7%E9%A2%98/note/No278_is-bad-version.md)
+- [No.88 合并两个有序数组](note/No88_merge.md)
+- [No.278 第一个错误的版本](note/No278_is-bad-version.md)

leetcode刷题/note/No268_missing-number.md

@@ -0,0 +1,44 @@
+# No.268 缺失数字
+
+给定一个包含 0, 1, 2, ..., n 中 n 个数的序列，找出 0 .. n 中没有出现在序列中的那个数。
+
+## 示例
+
+示例 1:
+
+```
+输入: [3,0,1]
+输出: 2
+```
+
+示例 2:
+```
+输入: [9,6,4,2,3,5,7,0,1]
+输出: 8
+```
+说明:
+你的算法应具有线性时间复杂度。你能否仅使用额外常数空间来实现？
+
+
+
+## 解题思路
+
+用数学的思维方式，假如没有数字缺失，则total满足等差数列的求和公式。减去原数组的和，则剩下的数为缺失的数字。
+
+代码如下：
+
+```javascript
+/**
+ * @param {number[]} nums
+ * @return {number}
+ */
+var missingNumber = function(nums) {
+    let n = nums.length+1;
+    // 等差数列求和
+    let total = (n-1)*n/2;
+    for (let i = 0; i < n-1; i++) {
+      total -=  nums[i];
+    }
+    return total;
+};
+```