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).

 1 public class Solution {
 2     public int threeSumClosest(int[] num, int target) {
 3         if(num == null || num.length < 3) return 0;
 4         int min = Integer.MAX_VALUE, len = num.length;
 5         Arrays.sort(num);
 6         for(int i = 0; i < len - 2; i ++){
 7             int goal = target - num[i];
 8             int j = i + 1, k = len - 1;
 9             while(j < k){
10                 min = Math.abs(min) < Math.abs(target - num[i] - num[j] - num[k]) ? min : (target - num[i] - num[j] - num[k]);
11                 if(num[j] + num[k] < goal) j ++;
12                 else if(num[j] + num[k] > goal) k --;
13                 else return target;
14             }
15         }
16         return target - min;
17     }
18 }

 

posted on 2014-08-05 10:01  Step-BY-Step  阅读(100)  评论(0)  编辑  收藏  举报

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