Given an array of distinct integers arr, where arr is sorted in ascending order, return the smallest index i that satisfies arr[i] == i. If there is no such index, return -1. Example 1: Input: arr = [-10,-5,0,3,7] Output: 3 Explanation: For the given array, arr[0] = -10, arr[1] = -5, arr[2] = 0, arr[3] = 3, thus the output is 3. Example 2: Input: arr = [0,2,5,8,17] Output: 0 Explanation: arr[0] = 0, thus the output is 0. Example 3: Input: arr = [-10,-5,3,4,7,9] Output: -1 Explanation: There is no such i that arr[i] == i, thus the output is -1. Constraints: 1 <= arr.length < 104 -109 <= arr[i] <= 109 Follow up: The O(n) solution is very straightforward. Can we do better?