human
Solve in Python:
A peak element is an element that is greater than its neighbors.

Given an input array nums, where nums[i] ≠ nums[i+1], find a peak element and return its index.

The array may contain multiple peaks, in that case return the index to any one of the peaks is fine.

You may imagine that nums[-1] = nums[n] = -∞.

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: 1 or 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.

Note:

Your solution should be in logarithmic complexity.

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What is a Python program to find a peak element and return its index?
assistant
#Here is Python program to find a peak element and return its index.

class Solution:
     def findPeakElement(self, nums):
         """
         :type nums: List[int]
         :rtype: int
         """
         if len(nums) == 1:
             return 0
         left, right = 0, len(nums) - 1
         length = len(nums)
         while left + 1 < right:
             mid = (left + right) // 2
             if mid == 0:
                 if nums[mid] > nums[mid + 1]:
                     return 0
                 else:
                     left = mid + 1
             elif mid == length - 1:
                 if nums[-1] > nums[-2]:
                     return mid
                 else:
                     right = mid - 1
             elif nums[mid] > nums[mid - 1] and nums[mid] > nums[mid + 1]:
                 return mid
             elif nums[mid] < nums[mid - 1] and nums[mid] < nums[mid + 1]:
                 right = mid - 1
             elif nums[mid] > nums[mid + 1]:
                 right = mid - 1
             else:
                 left = mid + 1
         for idx in range(left, right + 1):
             if idx == 0 and nums[idx] > nums[idx + 1]:
                 return 0
             if idx == length - 1 and nums[-1] > nums[-2]:
                 return idx
             if nums[idx] > nums[idx - 1] and nums[idx] > nums[idx + 1]:
                 return idx