Formatted question description: https://leetcode.ca/all/704.html

# 704. Binary Search (Easy)

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].

Related Topics:
Binary Search

Similar Questions:

## Solution 1.

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

// Time: O(logN)
// Space: O(1)
class Solution {
public:
int search(vector<int>& A, int target) {
int L = 0, R = A.size();
while (L <= R) {
int M = (L + R) / 2;
if (A[M] == target) return M;
if (A[M] < target) L = M + 1;
else R = M - 1;
}
return -1;
}
};


Java

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