Sum of the 3 Closest

Given an array nums of n integers and an integer target, find three integers in nums such that the sum is closest to target. Return the sum of the three integers. You may assume that each input would have exactly one solution.

Example:

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)

Write your solution:

function main (nums, target) {
    return;
}

function main (nums, target) { return; }

Test Case 1

Input: [-1,2,1,-4], 1
Output: 2

Test Case 2

Input: [-1,20,10,14,12,13], 13
Output: 21

Solution

Complexity:

• Time complexity: O(n^2).
• Space complexity: O(1).

function threeSumClosest(nums, target) {
    let len = nums.length;
    let res = nums[0] + nums[1] + nums[2];
    let sum = 0;
    let l = 0;
    let r = 0;

    nums.sort((a, b) => a - b);

    for (let i = 0; i < len - 2; i++) {
        if (i > 0 && nums[i] === nums[i - 1]) continue;
        l = i + 1;
        r = len - 1;
        while (l < r) {
            sum = nums[i] + nums[l] + nums[r];
            if (sum < target) {
                l++;
            } else if (sum > target) {
                r--;
            } else {
                return sum;
            }
            if (Math.abs(sum - target) < Math.abs(res - target)) res = sum;
        }
    }
    return res;
}