16. 3Sum Closest

Input: nums = [-1,2,1,-4], target = 1
Output: 2
Explanation: The sum that is closest to the target is 2. (-1 + 2 + 1 = 2).

Rust Solution

struct Solution;

use std::i32;

impl Solution {
    fn three_sum_closest(mut nums: Vec<i32>, target: i32) -> i32 {
        nums.sort_unstable();
        let n = nums.len();
        let mut res = 0;
        let mut diff = i32::MAX;
        for i in 0..n - 2 {
            let mut l = i + 1;
            let mut r = n - 1;
            while l < r {
                let sum = nums[l] + nums[r] + nums[i];
                if sum == target {
                    return target;
                }
                if (sum - target).abs() < diff {
                    diff = (sum - target).abs();
                    res = sum;
                }
                if nums[l] + nums[r] > target - nums[i] {
                    r -= 1;
                } else {
                    l += 1;
                }
            }
        }
        res
    }
}

#[test]
fn test() {
    let nums = vec![-1, 2, 1, -4];
    let target = 1;
    let res = 2;
    assert_eq!(Solution::three_sum_closest(nums, target), res);
}