[leetcode]581. Shortest Unsorted Continuous Subarray

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本文介绍了一个LeetCode上的算法题，即找到一个整数数组中最短的连续子数组，对该子数组进行排序后能使整个数组变为有序。文章通过示例详细解释了问题，并提供了一段C++代码实现，该算法能够找出需要排序的子数组并返回其长度。

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

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

class Solution {
public:
    int findUnsortedSubarray(vector<int>& nums) {
        int shortest = 0;

        int left = 0, right = nums.size() - 1;
        while (left < nums.size() - 1 && nums[left] <= nums[left + 1]) { left++; }
        while (right > 0 && nums[right] >= nums[right - 1]) { right--; };

        if (right > left) {
            int vmin = INT32_MAX, vmax = INT32_MIN;
            for (int i = left; i <= right; ++i) {
                if (nums[i] > vmax) {
                    vmax = nums[i];
                }
                if (nums[i] < vmin) {
                    vmin = nums[i];
                }
            }

            while (left >= 0 && nums[left] > vmin) { left--; };
            while (right < nums.size() && nums[right] < vmax) { right++; };

            shortest = right - left - 1;
        }

        return shortest;
    }
};