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 peak elements**. 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 = [5,4,3,2,1] Output: 0 Explanation: 5 is greater than its only neighbor 4, so index 0 is a peak. **Example 3:** Input: nums = [1,2,3,4,5] Output: 4 Explanation: 5 is greater than its only neighbor 4, so index 4 is a peak.