POJ1161（并查集）

#include <iostream>
using namespace std;
int parent[30001];
int suspect[30001];
 
int find(int x)
{
   if(parent[x] == x)
   {
      return x;
   }
   else
   {
      return parent[x] = find(parent[x]);
   }
}
 
void Union(int a, int b)
{
   int x = find(a);
   int y = find(b);
   if(x == y)
   {
      return;
   }
   parent[y] = x;
   suspect[x] = suspect[x] + suspect[y];
}
 
int main()
{
   int m, n;
   int a, b, c;
   int x;
   int i;
   while(cin >> m >> n)
   {
      if(m == 0 && n == 0)
      {
          break;
      }
      
      for(i = 0; i <= m; i++)
      {
        parent[i] = i;
        suspect[i] = 1;
      }
      
      while(n--)
      {
        cin >> a >> b;
        a--;
        while(a--)
        {
           cin >> c ;
           if(find(c) != find(b))
           {
               Union(c, b);
           }
        }
      }
 
      cout << suspect[find(0)] << endl;
   }
   return 0;
}