# 3Sum Closest

## Problem

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.

## Example

For 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).

## Note

You may assume that each input would have exactly one solution.

## Challenge

O(n^2) time, O(1) extra space

## Code - Java

public class Solution {
/**
* @param numbers: Give an array numbers of n integer
* @param target   : An integer
* @return : return the sum of the three integers, the sum closest target.
*/
public int threeSumClosest(int[] numbers, int target) {
int min = Integer.MAX_VALUE;
int sum = 0;

Arrays.sort(numbers);

for (int i = 0; i < numbers.length - 2; i++) {
int left = i + 1;
int right = numbers.length - 1;

while (left < right) {
int s = numbers[i] + numbers[left] + numbers[right];
if (Math.abs(s - target) < min) {
min = Math.abs(s - target);
sum = s;
}

if (s < target) {
left++;
} else {
right--;
}
}
}
return sum;
}
}