# 704 Binary Search

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, then return its index. Otherwise, return `-1`.

You must write an algorithm with `O(log n)` runtime complexity.

Example 1:

``````Input: nums = [-1,0,3,5,9,12], target = 9
Output: 4
Explanation: 9 exists in nums and its index is 4
``````

Example 2:

``````Input: nums = [-1,0,3,5,9,12], target = 2
Output: -1
Explanation: 2 does not exist in nums so return -1
``````

Constraints:

• `1 <= nums.length <= 104`
• `-104 < nums[i], target < 104`
• All the integers in `nums` are unique.
• `nums` is sorted in ascending order.
 `````` 1 2 3 4 5 6 7 8 9 10 11 12 13 `````` ``````class Solution: def search(self, nums: List[int], target: int) -> int: low = 0 high = len(nums) - 1 while low <= high: mid = low + (high - low) // 2 if nums[mid] == target: return mid elif nums[mid] < target: low = mid + 1 else: high = mid - 1 return -1``````