leetcode -- 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 int threeSumClosest(int[] num, int target) {
 2         // Start typing your Java solution below
 3         // DO NOT write main() function
 4         Arrays.sort(num);
 5         int result = 0;
 6         int lastAbs = 65536;
 7         int len = num.length;
 8         for (int i = 0; i < len; i++) {
 9             int start = i + 1;
10             int end = len - 1;
11             while (start < end) {
12                 if (num[i] + num[start] + num[end] == target) {
13                     lastAbs = 0;
14                     result = target;
15                     start++;
16                     end--;
17                     return result;
18                 }
19                 if (num[i] + num[start] + num[end] > target) {
20                     if (Math.abs(num[i] + num[start] + num[end] - target) < lastAbs) {
21                         lastAbs = Math.abs(num[i] + num[start] + num[end] - target);
22                         result = num[i] + num[start] + num[end];
23                     }
24                     end--;
25                 }
26 
27                 if (num[i] + num[start] + num[end] < target) {
28                     if (Math.abs(num[i] + num[start] + num[end] - target) < lastAbs) {
29                         lastAbs = Math.abs(num[i] + num[start] + num[end]
30                                 - target);
31                         result = num[i] + num[start] + num[end];
32                     }
33                     start++;
34                 }
35 
36             }
37         }
38         return result;
39     }

 

posted @ 2013-07-03 17:34  feiling  阅读(246)  评论(0)  编辑  收藏  举报