poj 1611 分类： poj templates 2015-04-03 14:48 33人阅读 评论(0) 收藏

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并查集，启发式合并

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#include<map>
#include<string>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<ctime>
#include<cmath>
#include<iostream>
#include<algorithm>

const int MAXN = 3e4+5;

int n , m;
int fa[MAXN] = {0};
int size[MAXN] = {0};

int find_fa(int x)
{
    if(fa[x] == x)return x;
    else
    {  
      fa[x] = find_fa(fa[x]);
      return fa[x];
    }
}
void gather(int u,int v)
{
    u = find_fa(u), v = find_fa(v);
    if(u == v)return;

    if(size[u] < size[v])std::swap(u,v);

    fa[v] = u, size[u] += size[v];
}
int main()
{
#ifndef ONLINE_JUDGE
    freopen("poj1611.in","r",stdin);
    freopen("poj1611.out","w",stdout);
#endif

    while(1)
    {
      scanf("%d%d",&n,&m);
      if(!n && !m)break;

      for(int i = 1;  i <= n ; i++)fa[i] = i, size[i] = 1;

      for(int i = 1; i <= m;i++)
      {
        int len, h;
        scanf("%d",&len);
        if(!len)continue;

        scanf("%d",&h); h++; 
        for(int j = 1; j < len; j++)
        {
            int s; scanf("%d",&s);
            ++s; gather(h,s);
        }
      }
      printf("%d\n",size[find_fa(1)]);

    }

#ifndef ONLINE_JUDGE
    fclose(stdin);
    fclose(stdout);
#endif
    return 0;
}

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