Find Peak Element

Problem Statement

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.

Leetcode link

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
• -2³¹ <= nums[i] <= 2³¹ - 1
• nums[i] != nums[i + 1] for all valid i.

Code

Python Code

class Solution:
        def findPeakElement(self, nums):
        """
        :type nums: List[int]
        :rtype: int
        """
        if len(nums)<2:
            return 0

        elif len(nums)==2:
            return nums.index(max(nums))

        for i in range(len(nums)):
            if i == 0 and nums[i]>nums[i+1]: return i
            elif (i>0 and i<len(nums)-1) and (nums[i] > nums[i+1]) and (nums[i] > nums[i-1]): return i
            elif (i == len(nums)-1) and (nums[i]>nums[i-1]): return i