3sum-closest.js

/*

https://leetcode.com/problems/3sum-closest/
--
Given an integer array nums of length n 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.

Constraints:

3 <= nums.length <= 500
-1000 <= nums[i] <= 1000
-10⁴ <= target <= 10⁴

 */

const threeSumClosest = (nums, target) => {
  nums = nums.sort((a, b) => a - b);

  let result = Infinity, resultDelta = Infinity;

  for (let index = 0; index < nums.length; index++) {
    const num = nums[index];
    const rest = nums.slice(index + 1);
    const closestSum = twoSum(rest, target - num) + num;
    const delta = Math.abs(target - closestSum);

    if (delta < resultDelta) {
      result = closestSum;
      resultDelta = delta;
    }
  }

  return result;
}

const twoSum = (nums, target) => {
  let left = 0,
    right = nums.length - 1,
    closest = Infinity,
    closestDelta = Infinity;

  while (left < right) {
    const sum = nums[left] + nums[right];
    if (sum === target) return sum;

    const delta = Math.abs(sum - target);
    if (delta < closestDelta) {
      closest = sum;
      closestDelta = delta;
    }

    (sum < target) ? left++ : right--;
  }

  return closest;
}

nums = [833,736,953,-584,-448,207,128,-445,126,248,871,860,333,-899,463,488,-50,-331,903,575,265,162,-733,648,678,549,579,-172,-897,562,-503,-508,858,259,-347,-162,-505,-694,300,-40,-147,383,-221,-28,-699,36,-229,960,317,-585,879,406,2,409,-393,-934,67,71,-312,787,161,514,865,60,555,843,-725,-966,-352,862,821,803,-835,-635,476,-704,-78,393,212,767,-833,543,923,-993,274,-839,389,447,741,999,-87,599,-349,-515,-553,-14,-421,-294,-204,-713,497,168,337,-345,-948,145,625,901,34,-306,-546,-536,332,-467,-729,229,-170,-915,407,450,159,-385,163,-420,58,869,308,-494,367,-33,205,-823,-869,478,-238,-375,352,113,-741,-970,-990,802,-173,-977,464,-801,-408,-77,694,-58,-796,-599,-918,643,-651,-555,864,-274,534,211,-910,815,-102,24,-461,-146];
target = -7111;
expected = -2960;
actual = threeSumClosest(nums, target);
console.assert(actual === expected, '%o', { nums, expected, actual });