原题链接在这里：

题目：

Given an integer array, you need to find one continuous subarray that if you only sort this subarray in ascending order, then the whole array will be sorted in ascending order, too.

You need to find the shortest such subarray and output its length.

Example 1:

Input: [2, 6, 4, 8, 10, 9, 15]Output: 5Explanation: You need to sort [6, 4, 8, 10, 9] in ascending order to make the whole array sorted in ascending order.

Note:

1. Then length of the input array is in range [1, 10,000].
2. The input array may contain duplicates, so ascending order here means <=.

题解：

index e标记最后没有ascending的位置.

index s标记最初没有decending的位置.

若nums 本来已经sort了，那么s 和 e不会更新.

Time Complexity: O(nums.length). Space: O(1).

AC Java:

1 class Solution { 2     public int findUnsortedSubarray(int[] nums) { 3         if(nums == null || nums.length == 0){ 4             return 0; 5         } 6          7         int s = -1; 8         int e = -2; 9         int len = nums.length;10         int max = nums[0];11         int min = nums[len-1];12         for(int i = 0; i