16.3-sum-closest.js

/*
 * @lc app=leetcode id=16 lang=javascript
 *
 * [16] 3Sum Closest
 *
 * https://leetcode.com/problems/3sum-closest/description/
 *
 * algorithms
 * Medium (45.80%)
 * Likes:    2034
 * Dislikes: 138
 * Total Accepted:    466.5K
 * Total Submissions: 1M
 * Testcase Example:  '[-1,2,1,-4]\n1'
 *
 * 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 1:
 *
 *
 * 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).
 *
 *
 *
 * Constraints:
 *
 *
 * 3 <= nums.length <= 10^3
 * -10^3 <= nums[i] <= 10^3
 * -10^4 <= target <= 10^4
 *
 *
 */

// @lc code=start
/**
 * @param {number[]} nums
 * @param {number} target
 * @return {number}
 */
var threeSumClosest = function (nums, target) {
  //get the default result
  let resSum = Infinity;
  nums.sort((a, b) => a - b);
  for (let i = 0; i < nums.length - 2; i++) {
    //2 pointer
    let start = i + 1,
      end = nums.length - 1;
    while (start < end) {
      let sum = nums[i] + nums[start] + nums[end];
      if (sum > target) {
        end--;
      } else {
        start++;
      }
      if (Math.abs(sum - target) < Math.abs(resSum - target)) {
        resSum = sum;
      }
    }
  }
  return resSum;
};
// @lc code=end