162. Find Peak Element

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

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.

Constraints:

• 1 <= nums.length <= 1000
• -2^31 <= nums[i] <= 2^31 - 1
• nums[i] != nums[i + 1] for all valid i.

Solution

class Solution:
    def findPeakElement(self, nums: list[int]) -> int:
        left, right = 0, len(nums) - 1
        while left < right:
            mid = (left + right) // 2
            if nums[mid] < nums[mid + 1]:
                left = mid + 1
            else:
                right = mid

        return left