Three Sum Closet

Description:

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

EXAMPLE:

Given array S = {-1 2 1 -4}, and target = 1.

The sum that is closest to the target is 2. (-1 + 2 + 1 = 2).

Solution

Simply modify the code for three sum and add the comparison between the sum and the target.

public class Solution {
    public int threeSumClosest(int[] nums, int target) {
        Arrays.sort(nums);
        int res = nums[0] + nums[1] + nums[2];
        for (int i = 0 ; i < nums.length - 1; i ++) {
            if(i == 0 || (i > 0 && nums[i] != nums[i-1])) {
                int lo = i + 1, hi = nums.length - 1;
                while(lo < hi) {
                    int sum = nums[lo] + nums[hi] + nums[i];
                    if(sum > target) hi--;
                    else lo++;
                    if (Math.abs(sum-target) < Math.abs(res - target)) {
                        res = sum;
                    }
                }
            }
        }
        return res;
    }
}