# Leetcode 162. Find Peak Element

## 題解

### 鎖定左邊界

class Solution:
    def findPeakElement(self, nums: List[int]) -> int:
        # Time complexity: O(logn)
        # Space complexity: o(1)
        n = len(nums)
        left = 0
        right = n - 2
        ans = 0
        while left <= right:
            mid = left + (right - left) // 2
            if nums[mid] < nums[mid+1]:
                left = mid + 1
                ans = left
            else:
                right = mid - 1
        return ans