Given an array of integers nums which is sorted in ascending order, and an integer target, write a function to search target in nums. If target exists, return its index. Otherwise, return -1.
You must write an algorithm with O(log n) runtime complexity.
Input: nums = [-1, 0, 3, 5, 9, 12], target = 9
Output: 4
9 exists in nums and its index is 4.
Input: nums = [-1, 0, 3, 5, 9, 12], target = 2
Output: -1
2 does not exist in nums so return -1.
1 ≤ nums.length ≤ 10⁴-10⁴ < nums[i], target < 10⁴nums are unique.nums is sorted in ascending order.4