162.py

# 162. Find Peak Element
# 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.

class Solution:
    def firstPeakElement(self, nums):
        low = 0
        high = len(nums) - 1
        while low < high:
            mid = (low + high) // 2
            if nums[mid] > nums[mid + 1]:
                high = mid
            else:
                low = mid + 1
        return low

solution = Solution()
result = solution.firstPeakElement([1,2,1,3,5,6,4])
print(result)