Leetcode:162. looking for peak [two points looking for peak]

analysis

Two points to find the peak , Always go to the higher side , Always reach the peak
Then notice that l <= r or l < r or l < r - 1

ac code

class Solution:
    def findPeakElement(self, nums: List[int]) -> int:
        n = len(nums)

        #  People go high , Always reach the peak 
        def get(i):
            if i == -1 or i == n:
                return -inf
            return nums[i]

        l, r, ans = 0, n - 1, -1

        while l <= r:
            mid = (l + r) // 2
            if get(mid - 1) < get(mid) > get(mid + 1):
                ans = mid
                break
            
            if get(mid) < get(mid + 1):
                l = mid + 1
            else:
                r = mid - 1
        
        return ans

summary

Two points to find the peak