First and Last Position Search

Problem

Given a sorted array of integers nums in non-decreasing order and an integer target, return a list of two integers representing the first and last index of target in nums. If target does not exist in the array, return [-1, -1]. Your solution should run in O(log n) time.

Constraints

• 0 <= nums.length <= 10^5
• -10^9 <= nums[i] <= 10^9
• nums is sorted in non-decreasing order
• -10^9 <= target <= 10^9
• Expected time complexity is O(log n)