find-peak-element_162.py

# A peak element is an element that is strictly greater than its neighbors.

# Given a 0-indexed integer array nums, find a peak element, and return its index. If the array contains multiple peaks, return the index to any of the peaks.

# You may imagine that nums[-1] = nums[n] = -∞. In other words, an element is always considered to be strictly greater than a neighbor that is outside the array.

# You must write an algorithm that runs in O(log n) time.

# Example 1:

# Input: nums = [1,2,3,1]
# Output: 2
# Explanation: 3 is a peak element and your function should return the index number 2.
# Example 2:

# Input: nums = [1,2,1,3,5,6,4]
# Output: 5
# Explanation: Your function can return either index number 1 where the peak element is 2, or index number 5 where the peak element is 6.

# ---------------------------------------Runtime 52 ms Beats 51.5% Memory 16.3 MB Beats 96.71%---------------------------------------


from typing import List


class Solution:
    def findPeakElement(self, nums: List[int]) -> int:
        start, end = 0, len(nums) - 1

        while start < end:
            middle = (start + end) // 2

            if nums[middle] > nums[middle + 1]:
                end = middle
            else:
                start = middle + 1
        return end