poj1611 The Suspects (并查集)

#include<iostream>

using namespace std;

int f[30000],rank[30000];

void makeset(int x)
{
int i;
for(i=0;i<x;i++)
f[i]=i,rank[i]=0;
}

int findset(int x)
{
if(x!=f[x])
f[x]=findset(f[x]);
return f[x];
}

void unionset(int a,int b)
{
int fa=findset(a);
int fb=findset(b);
if(rank[fa]>rank[fb])f[fb]=fa;
else
{
if(rank[fa]==rank[fb])rank[fb]++;
f[fa]=fb;
}
}

int main()
{
int n,m;
while(cin>>n>>m,n||m)
{
int cnt=1;//′ú±í?Dè?êy
int i,j;
makeset(n);
for(i=0;i<m;i++)
{
int t,a,b;
cin>>t;
cin>>a;
for(j=1;j<t;j++)
{
cin>>b;
unionset(a,b);
a=b;
}
}
int st=findset(0);
for(i=1;i<n;i++)
if(st==findset(i))
cnt++;
cout<<cnt<<endl;
}
return 0;
}