Binary Search
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# LeetCode #704: Binary Search (C/C++).

easy

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: 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.

## Solution

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 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; } };