ShortestUnsortedContinuousSubarray

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 <=.

思路：

要求这么一个子串，如果这个子串按升序排列好了，那么整个数组也升序排列好。我们只需要对数组进行一次排序保存到新数组中，然后比较新旧数组同一下标处的元素是否相同。一旦第一次出现不同就记录下来。可以分别得到首，尾两个元素的下标值i,j，那么所求子串的长度就是i-j+1.

import java.util.Arrays;public class ShortestUnsortedContinuousSubarray {    public int findUnsortedSubarray(int[] nums) {    int[] temp = Arrays.copyOf(nums, nums.length);    Arrays.sort(temp);    int i=0, j=temp.length-1;    while(i<nums.length && nums[i] == temp[i])    i++;    while(i<j && nums[j] == temp[j])    j--;    return j-i+1;    }}