README.md

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].

Solutions (Rust)

1. Binary Search

impl Solution {
    pub fn search(nums: Vec<i32>, target: i32) -> i32 {
        let mut head = 0;
        let mut tail = nums.len() as i32 - 1;
        while head <= tail {
            if target == nums[(head + tail) as usize / 2] {
                return (head + tail) / 2;
            } else if target > nums[(head + tail) as usize / 2] {
                head = (head + tail) / 2 + 1;
            } else if target < nums[(head + tail) as usize / 2] {
                tail = (head + tail) / 2 - 1;
            }
        }
        -1
    }
}