This problem was asked by AirBNB.
Given a sorted array, A, with possibly duplicated elements, find the indices of the first and last occurrences of a target element, x.
Return -1 if the target is not found.
Input: A = [1,3,3,5,7,8,9,9,9,15], target = 9
Output: [6,8]
Input: A = [100, 150, 150, 153], target = 150
Output: [1,2]
Input: A = [1,2,3,4,5,6,10], target = 9
Output: [-1, -1]