Leetcode no. 16

16. 3Sum Closest

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.

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).

public class Solution {
public int threeSumClosest(int[] nums, int target) {
if (nums.length< 3) return 0;
Arrays.sort(nums);
int gap=Integer.MAX_VALUE;
for (int i = 0; i < nums.length; i++) {
if (i>0 && nums[i]==nums[i-1]) continue;
int newtarget= target-nums[i];
int j=i+1;
int k= nums.length-1;
while (j<k){
while (j<k && nums[j]+nums[k]<newtarget) j++;
if (j>i+1 && newtarget-nums[j-1]-nums[k]<Math.abs(gap)){ gap= newtarget-nums[j-1]-nums[k]; }
if (j<k && nums[j]+nums[k]-newtarget<Math.abs(gap)){ gap= newtarget-nums[j]-nums[k]; }
if (gap==0) return target;
while (j<k && nums[j]+nums[k]>newtarget) k--;
if (k+1<nums.length && nums[j]+nums[k+1]-newtarget<Math.abs(gap)){ gap= newtarget-nums[j]-nums[k+1]; }
if (j<k && newtarget-nums[j]-nums[k]<Math.abs(gap)){ gap= newtarget-nums[j]-nums[k]; }
if (gap==0) return target;
}
}
return target-gap;
}
}