581. Shortest Unsorted Continuous Subarray刷题笔记

子串为ABC，考虑AB和BC

class Solution:
    def findUnsortedSubarray(self, nums: List[int]) -> int:
        
        end = 0
        prev = nums[0]
        for i in range(1,len(nums)):
            if nums[i]>=prev:
                prev = nums[i]
            else:
                end = i
        if end == 0:
            return 0
        start = len(nums)-1
        prev = nums[-1]
        for i in range(len(nums)-2,-1,-1):
            if nums[i]<=prev:
                prev = nums[i]
            else:
                start = i
        return end - start +1