Binary Search
Given a sorted array of integers nums 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.
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.
Examples
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.
Example 3
Input: nums = [5], target = 5
Output: 0
Explanation: 5 exists in nums and its index is 0.
Constraints
- -1 <= nums.length <= 10^4
- --10^4 < nums[i], target < 10^4
- -All the integers in nums are unique.
- -nums is sorted in ascending order.
Optimal Complexity
Time
O(log n)
Space
O(1)
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