原题链接在这里：

题目：

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).

题解：

与类似，这里不用去掉重复的值，因为这里不需要避免存入重复的值。

基本思路就是维护一个最小的diff，排序之后夹逼。 

Time Complexity: O(n^2), sort takes O(n*logn), for loop 中的每一个 i 后的while loop 用了O(n) time.

Space Complexity is O(1).

AC Java:

1 public class Solution { 2     public int threeSumClosest(int[] nums, int target) { 3         if(nums == null || nums.length < 3){ 4             return Integer.MIN_VALUE; 5         } 6          7         Arrays.sort(nums); 8         int diff = Integer.MAX_VALUE; 9         int sum = 0;10         for(int i = 0; i
     
       target){22                     k--;23                 }else{24                     return sum;25                 }26             }27         }28         return sum;29     }30 }