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]`.

704. Binary Search
``````struct Solution;
use std::cmp::Ordering::*;

impl Solution {
fn search(nums: Vec<i32>, target: i32) -> i32 {
let n = nums.len();
let mut l: usize = 0;
let mut r: usize = nums.len() - 1;
while l <= r {
let mid = (l + r) / 2;
match nums[mid].cmp(&target) {
Equal => {
return mid as i32;
}
Less => {
if mid + 1 > n - 1 {
break;
}
l = mid + 1;
}
Greater => {
if mid < 1 {
break;
}
r = mid - 1;
}
}
}
-1
}
}

#[test]
fn test() {
let nums = vec![-1, 0, 3, 5, 9, 12];
let target = 9;
assert_eq!(Solution::search(nums, target), 4);

let nums = vec![-1, 0, 3, 5, 9, 12];
let target = 2;
assert_eq!(Solution::search(nums, target), -1);
}
``````