Peak Index in a Mountain Array

An array `arr` is a **mountain** if: - `arr.length >= 3` - There exists some `i` with `0 < i < arr.length - 1` such that: - `arr[0] < arr[1] < ... < arr[i - 1] < arr[i]` - `arr[i] > arr[i + 1] > ... > arr[arr.length - 1]` Given a mountain array `arr`, return the index `i` such that `arr[0] < arr[1] < ... < arr[i - 1] < arr[i] > arr[i + 1] > ... > arr[arr.length - 1]`. You must solve it in `O(log(arr.length))` time complexity. ### Constraints - `3 <= arr.length <= 10^5` - `0 <= arr[i] <= 10^6` - `arr` is guaranteed to be a mountain array. ### Input Format A single line containing space-separated integers representing `arr`. ### Output Format Print the index of the mountain peak.