codeforces-C. News Distribution-2019.5.15

模板题：并查集

题意：给你n个用户和m个组，让你求出如果第i个人传播消息，会有几个人知道。http://codeforces.com/contest/1167/problem/C

思路：简单的并查集

#include <cstdio>
#include<bits/stdc++.h>
const int maxnn = 3000000;
using namespace std;
typedef long long ll;
int pre[600000];
int rank1[600000];
int _find(int x)
{
    int a=x;
    while(x!=pre[x])
    {
        x=pre[x];
        rank1[a]++;
    }
    return x;
}
int _find1(int x)
{

    int a=x;
    while(x!=pre[x])
    {
        x=pre[x];
    }
    return x;

}
int main()
{
    int n,m;
    for(int i=0;i<600000;i++){pre[i]=i;rank1[i]=1;}
    scanf("%d%d",&n,&m);
    for(int i=0;i<m;i++)
    {
        int t;
        scanf("%d",&t);
        if(t==0)continue;
        int k,kk;
        scanf("%d",&k);
        for(int j=0;j<t-1;j++)
        {
            scanf("%d",&kk);
            int a=_find(k);
            int b=_find(kk);
            if(a!=b)
            {
                if(rank1[a]>rank1[b])
                {
                    pre[b]=a;
                    rank1[a]+=rank1[b];
                }

                else
                {
                    pre[a]=b;
                    rank1[b]+=rank1[a];
                }
            }
        }
    }
    for(int i=1;i<=n;i++)
    {
        pre[i]=_find1(pre[i]);
        rank1[i]=rank1[_find(pre[i])];
    }
    for(int i=1;i<=n;i++)
    {
        if(i==1)printf("%d",rank1[i]);
        else  printf(" %d",rank1[i]);
    }
    return 0;
}