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] = -Infinity`. 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 1 (peak value 2) or index 5 (peak value 6).
Constraints
- 1 <= nums.length <= 1000
- -2^31 <= nums[i] <= 2^31 - 1
- nums[i] != nums[i + 1] for all valid i.