public class Solution {

public int threeSumClosest(int[] nums, int target) {

if(nums == null || nums.length < 3) throw new IllegalArgumentException("xxx");

Arrays.sort(nums);

int n = nums.length;

int minDiff = Integer.MAX_VALUE;

int candidate = 0;

for(int i = 0; i < n; i++){

int j = i+1;

int k = n-1;

while(j < k){

int t = nums[i] + nums[j] + nums[k];

if(t == target) return t;

// keep track of all potential candidates

if(Math.abs(t-target) < minDiff){

minDiff = Math.abs(t-target);

candidate = t;

}

if(t < target) j++;

else k--;

}

}

return candidate;

}

}