leetcode-852-山脉数组的峰顶索引

题目

https://leetcode.cn/problems/peak-index-in-a-mountain-array/description/

题解

class Solution:
    def peakIndexInMountainArray(self, arr: List[int]) -> int:
        n = len(arr)
        left,right =0,n-1 
        res = 0
        while left<right:
            now = (left+right)//2
            if arr[now-1]<arr[now]<arr[now+1]:
                left = now
            elif arr[now-1]>arr[now]>arr[now+1]:
                right = now
            else:
                res = now
                break
        return res