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).
这道题和上一道3sum很向，只要稍微改变一下就好了

 1 public class Solution {
 2     public int threeSumClosest(int[] num, int target) {
 3         int result = Integer.MAX_VALUE;                    //最后返回的结果
 4         int distance = Integer.MAX_VALUE;
 5         Arrays.sort(num);                                 //对数组进行升序排序
 6         boolean findTarget = false;
 7         
 8         for(int i = 0; i < num.length; i++){
 9             int j = i + 1;
10             int k = num.length - 1;                        //双指针
11             while(j < k){
12                 int sum = num[i] + num[k] + num[j];
13                 if(target == sum){                        //等于target直接返回target的值
14                     findTarget = true;
15                     result = target;
16                     break;
17                 }
18                 else if(sum > target){                    //sum比target大k前移,同时更新result,和距离
19                     if(Math.abs(sum - target) < distance){
20                         distance = Math.abs(sum - target);
21                         result = sum;
22                     }
23                     k--;    
24                 }
25                 else{                                    //sum比target小，更新result和距离
26                     if(Math.abs(sum - target) < distance){
27                         distance = Math.abs(sum - target);
28                         result = sum;
29                     }
30                     j++;
31                 }
32             }
33             if(findTarget)
34                 break;
35         }
36         
37         return result;
38     }
39 }