题目描述：
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).
解题思路：
这个跟3Sum的思路差不多，不过实现的过程就简单多了。外面一个大的循环，里面也是从两边开始，如果三个数之和减去目标值的绝对值较小，则更新之并记录此三个数之和。
代码如下：
1 public class Solution { 2 public int threeSumClosest(int[] nums, int target) { 3 int length = nums.length; 4 int min = Integer.MAX_VALUE; 5 int left, right, comp, result = 0; 6 7 if (length < 3) 8 return 0; 9 Arrays.sort(nums); 10 11 for (int i = 0; i < length - 2; i++) { 12 left = i + 1; 13 right = length - 1; 14 while (left < right) { 15 comp = nums[i] + nums[left] + nums[right]; 16 if (Math.abs(comp - target) < min){ 17 min = Math.abs(comp - target); 18 result = comp; 19 } 20 if (comp > target) 21 right--; 22 else if (comp < target) 23 left++; 24 else 25 return target; 26 } 27 } 28 return result; 29 } 30 }
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).
Java [leetcode 16] 3Sum Closest
原文：http://www.cnblogs.com/zihaowang/p/4477995.html