zoj 1789 The Suspects

#include <iostream>
#include <cstdio>
using namespace std;

#define N 30010

int parent
;
int treeId
;

inline void init(int i)
{
treeId[i] = -1;
}

int find(int x)
{
if (treeId[x]>=0)
{
return treeId[x]=find(treeId[x]);
}
return x;
}

int main()
{
int n,m;

while (scanf("%d %d",&n,&m)==2)
{
if (n==0&&m==0) break;
for (int i=0;i<n;i++)
{
init(i);
}
while(m--)
{
int nm;
scanf("%d",&nm);
int father;
int fatherParent =0;
if(nm>0)
{
scanf("%d",&father);
nm--;
fatherParent= find(father);
}

while(nm--)
{
int tmp;
scanf("%d",&tmp);
int tmpParent = find(tmp);
if(tmpParent!=fatherParent)
{
treeId[fatherParent] += treeId[tmpParent];
treeId[tmpParent] = fatherParent;
}
}
}
printf("%d\n",-treeId[find(0)]);
}
return 0;
}