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. ```   **Constraints:** - `1 <= nums.length <= 1000` - `-231 <= nums[i] <= 231 - 1` - `nums[i] != nums[i + 1]` for all valid `i`.