Problem Statement

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.

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Examples

Example 1

Input:  nums = [-1, 0, 3, 5, 9, 12], target = 9
Output: 4

9 exists in nums and its index is 4.

Example 2

Input:  nums = [-1, 0, 3, 5, 9, 12], target = 2
Output: -1

2 does not exist in nums so return -1.

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Constraints

• 1 ≤ nums.length ≤ 10⁴
• -10⁴ < nums[i], target < 10⁴
• All the integers in nums are unique.
• nums is sorted in ascending order.