704. Binary Search

1. Description

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.

2. Example

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

3. 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

4. Solutions

My Accepted Solution

n = nums.size()
Time complexity: O(logn)
Space complexity: O(n)

class Solution {
public:
    int search(const vector<int> &nums, int target) {
        int result = -1;
        for (int left = 0, right = nums.size(); left < right;) {
            int mid = (left + right) / 2;
            if (nums[mid] == target) {
                return mid;
            }

            target < nums[mid] ? right = mid : left = mid + 1;
        }

        return result;
    }
};