852. Peak Index in a Mountain Array

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

Python

class Solution:
    def peakIndexInMountainArray(self, arr: List[int]) -> int:
        left, right = 0, len(arr)-1

        while left <= right:
            pivot = (left+right) >> 1

            if arr[pivot+1] < arr[pivot] and arr[pivot-1] < arr[pivot]:
                return pivot
            
            if arr[pivot+1] > arr[pivot]:
                left = pivot + 1
            else:
                right = pivot