**source:**https://leetcode.com/problems/binary-search**C/C++**

**Solution to LeetCode**problem

**704**.

**Binary Search**.

## Problem

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.

## Examples

**Example 1:**

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

Output:4Explanation: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 <= 10`

^{4}`-10`

^{4}< nums[i], target < 10^{4}- All the integers in
`nums`

are**unique**. `nums`

is sorted in ascending order.

## Solution

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class Solution {
public:
int search(vector<int>& nums, int target) {
int low = 0;
int high = nums.size() - 1;
int mid;
while (low <= high) {
mid = (low + high) / 2;
if (nums[mid] == target)
return mid;
if (nums[mid] > target)
high = mid - 1;
else
low = mid + 1;
}
return -1;
}
};