leetcode(2)3sum-closest

原创于 2016-06-22 09:46:59 发布 · 277 阅读

CC 4.0 BY-SA版权

本文介绍了一种寻找数组中三个整数之和最接近给定目标值的有效算法。通过排序和双指针技巧，确保了算法的时间效率。文章详细展示了如何遍历数组并调整指针位置来找到最佳解决方案。

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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.

import java.util.*;
public class Solution {
    public int threeSumClosest(int[] num, int target) {
		int min=Integer.MAX_VALUE;
        int tsum;
        int ca=0;
        Arrays.sort(num);
        for(int i=0;i<=num.length-3;i++)
            {
            int low =i+1,high=num.length-1;
            while(low<high)
                {
                 tsum=num[i]+num[low]+num[high];
                if(tsum==target)
                    {
                    return tsum;      
                }
                int dist =Math.abs(target-tsum);
                if(dist<min)
                    {
                    min=dist;
                   ca =tsum;
                }
                if(tsum<target)
                    {
                    low++;
                }
                else 
                    {
                    high--;
                }
                
            }
        }
        return ca;
       }
    }