Find Peak Element in an Array

[Question]: 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.

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.

// TC: O(log(N))
// SC: O(1)
func findPeakElement(_ nums: [Int]) -> Int {
    if nums.isEmpty  { return 0 }
    
    var left = 0
    var right = nums.count - 1
    
    while left < right {// from 0 to end of the array
        let mid = (left + right) / 2
        if nums[mid] < nums[mid + 1] { // 3 < 5
            left = mid + 1
        } else {
            right = mid
        }
    }
    
    return left
}