704. Binary Search

Problem

Given an array of integers nums which is sorted in ascending order, and an integer target, write a function to search target in nums. If target exists, then return its index. Otherwise, return -1.

You must write an algorithm with O(log n) runtime complexity.

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

Constraints:

• 1 <= nums.length <= 10⁴
• -10⁴ < nums[i], target < 10⁴
• All the integers in nums are unique.
• nums is sorted in ascending order.

Solution

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