# 704. Binary Search

Given a sorted (in ascending order) integer array `nums` of `n` elements and a `target` value, write a function to search `target` in `nums`. If `target` exists, then return its index, otherwise return `-1`.

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
``````

Note:

1. You may assume that all elements in `nums` are unique.
2. `n` will be in the range `[1, 10000]`.
3. The value of each element in `nums` will be in the range `[-9999, 9999]`.

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

Search in a Sorted Array of Unknown Size

https://leetcode.com/problems/binary-search

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