Leetcode-3Sum Closest

LiBlog發表於2014-11-28
LeetCode

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).
Have you met this question in a real interview?
 
Solution:
 1 public class Solution {
 2     public int threeSumClosest(int[] num, int target) {
 3         int len = num.length;
 4         Arrays.sort(num);
 5 
 6 
 7         int first = 0;
 8         int second = 1;
 9         int third = 2;
10         int res=num[first]+num[second]+num[third];
11         while (first<num.length-2){
12             second = first+1;
13             third = len-1;
14             while (second<third){
15                 int sum = num[first]+num[second]+num[third];
16                 if (sum==target) return target;
17                 if (Math.abs(sum-target)<Math.abs(res-target)) res = sum;
18                 if (sum>target){
19                     while (second<third && num[third]==num[third-1]) third--;
20                     third--;
21                 } else {
22                     while (second<third && num[second]==num[second+1]) second++;
23                     second++;
24                 }
25             }
26             while (first<num.length-2 && num[first]==num[first+1]) first++;
27             first++;
28         }
29         return res;
30         
31     }
32 }

 

相關文章