Virtual Friends (HDU3172)

最新推荐文章于 2025-08-13 18:07:46 发布

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最新推荐文章于 2025-08-13 18:07:46 发布

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文章标签： java php

原文链接：http://www.cnblogs.com/longl/p/7281254.html

本文介绍了一道关于社交网络模拟的算法题，通过使用并查集数据结构来跟踪和计算每个人社交网络的规模。题目涉及多个测试案例，需要处理大量数据并实时更新社交网络的大小。

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题目链接 http://acm.hdu.edu.cn/showproblem.php?pid=3172

Virtual Friends

Time Limit: 4000/2000 MS (Java/Others) Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 9227 Accepted Submission(s): 2669

Problem Description

These days, you can do all sorts of things online. For example, you can use various websites to make virtual friends. For some people, growing their social network (their friends, their friends' friends, their friends' friends' friends, and so on), has become an addictive hobby. Just as some people collect stamps, other people collect virtual friends.

Your task is to observe the interactions on such a website and keep track of the size of each person's network.

Assume that every friendship is mutual. If Fred is Barney's friend, then Barney is also Fred's friend.

Input

Input file contains multiple test cases.
The first line of each case indicates the number of test friendship nest.
each friendship nest begins with a line containing an integer F, the number of friendships formed in this frindship nest, which is no more than 100 000. Each of the following F lines contains the names of two people who have just become friends, separated by a space. A name is a string of 1 to 20 letters (uppercase or lowercase).

Output

Whenever a friendship is formed, print a line containing one integer, the number of people in the social network of the two people who have just become friends.

Sample Input

1 3 Fred Barney Barney Betty Betty Wilma

Sample Output

2 3 4

Source

University of Waterloo Local Contest 2008.09

注意此题多组数据，跟正常多的多组数据不同

AC代码：

#include<cstdio>
#include<iostream>
#include<map>
#include<cstring>
using namespace std;
const int maxn= 110000;
int pre[maxn],num[maxn];
char name1[30],name2[30];
string str1,str2;
map<string,int> mmap;
int find(int x)
{
    int r=x;
    while(r!=pre[r])
        r=pre[r];
    int i=x,j;
    while(pre[i]!=r)
    {
        j=pre[i];
        pre[i]=r;
        i=j;
    }

    return r;
}
void join(int x,int y)
{
    int fx=find(x),fy=find(y);
    if(fx!=fy)
    {
        pre[fx]=fy;
        num[fy]+=num[fx];
        num[fx]=0;

    }
    printf("%d\n",num[fy]);   ///每次都要输出
}

int main()
{
    int t,n;
    while(~scanf("%d",&t))    ///多组数据
    {
        while(t--)
        {
            mmap.clear();
            scanf("%d",&n);
            for(int i=1; i<maxn; i++)
                pre[i]=i,num[i]=1;
            int no=1;
            while(n--)
            {
                scanf("%s%s",name1,name2);
                str1=name1;
                str2=name2;
                if(mmap.find(str1)==mmap.end()&&mmap.find(str2)!=mmap.end())
                {
                    mmap[str1]=no++;
                    join(mmap[str1],mmap[str2]);

                }
                else if(mmap.find(str2)==mmap.end()&&mmap.find(str1)!=mmap.end())
                {
                    mmap[str2]=no++;
                    join(mmap[str1],mmap[str2]);

                }
                else if(mmap.find(str2)==mmap.end()&&mmap.find(str1)==mmap.end())
                {
                    mmap[str1]=no++;
                    mmap[str2]=no++;
                    join(mmap[str1],mmap[str2]);


                }
                else if(mmap.find(str2)!=mmap.end()&&mmap.find(str1)!=mmap.end())
                {
                    join(mmap[str1],mmap[str2]);

                }



            }

        }
    }


    return 0;
}