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).

思路：

3Sum变体，还是用两个指针来前后移动。
计算Math.abs(sum-target);
记录diff,和sum，return最小的diff的sum即可。

public class Solution {    public int threeSumClosest(int[] num, int target) {        int result = 0;        int min = Integer.MAX_VALUE;        Arrays.sort(num);        for(int i = 0; i< num.length-2;i++){            int j= i+1;             int k = num.length -1;            while(j<k){                int sum = num[i]+num[j]+num[k];                int diff = Math.abs(sum-target);                if(diff < min){                    result = sum;                    min = diff;                }                                if(sum>target){                    k--;                }else{                    j++;                }            }        }        return result;    }}