# 704-binary-search

## Question

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

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].

## Thought Process

1. Binary
1. Time complexity O(logn)
2. Space complexity O(1)

## Solution

``````class Solution {
public int search(int[] nums, int target) {
int lo = 0, hi = nums.length - 1;
while (lo <= hi) {
int mi = lo + (hi - lo) / 2;
if (nums[mi] == target) return mi;
else if (nums[mi] < target) lo = mi + 1;
else hi = mi - 1;
}
return -1;
}
}
``````