leetcode581

public class Solution {
    public int FindUnsortedSubarray(int[] nums) {
        int n = nums.Length, beg = -1, end = -2, min = nums[n - 1], max = nums[0];
            for (int i = 1; i < n; i++)
            {
                max = Math.Max(max, nums[i]);
                min = Math.Min(min, nums[n - 1 - i]);
                if (nums[i] < max)
                {
                    end = i;
                }
                if (nums[n - 1 - i] > min)
                {
                    beg = n - 1 - i;
                }
            }
            return end - beg + 1;
    }
}

https://leetcode.com/problems/shortest-unsorted-continuous-subarray/#/description

另外一种比较容易理解的方案:

public class Solution {
    public int FindUnsortedSubarray(int[] nums) {
        int n = nums.Length;
            var temp = new List<int>();
            for (int i = 0; i < n; i++)
            {
                temp.Add(nums[i]);
            }
            temp = temp.OrderBy(x => x).ToList();

            int start = 0;
            while (start < n && nums[start] == temp[start])
            {
                start++;
            }
            //正序找到第一个不同，确定start的位置


            int end = n - 1;
            while (end > start && nums[end] == temp[end])
            {
                end--;
            }
            //逆序找到第一个不同，确定end的位置

            return end - start + 1;
    }
}