poj 1466 Girls and Boys

这是一道求最大独立集的问题；

#include<iostream>
#include<cstdio>
#include<cstdlib>
#include<algorithm>
#include<cmath>
#include<queue>
#include<set>
#include<map>
#include<cstring>
#include<vector>
using namespace std;
bool G[524][524],visit[524];
int match[524];
bool path( int num , int N )
{
     for( int i = 1 ; i <= N ; i++ )
     {
         if( !visit[i] && G[num][i] )
         {
             visit[i] = true;
             if( match[i]==0 || path( match[i] , N ) )
             {
                 match[i] = num;
                 return true;        
             }        
         }        
     }    
     return false;
}
int main(  )
{
    int N,n,num,m;
    while( scanf( "%d",&N )==1 )
    {
       memset( G ,0 , sizeof( G )  );
       memset( match , 0 , sizeof( match ) );
       for( int i = 1 ; i <= N ; i ++ )
       {
           scanf( "%d: (%d)",&num , &n );
           for( int j = 0 ; j < n ; j ++ )
           {
                scanf( "%d",&m );
                G[num+1][m+1] = true;        
           }         
       }
       int ans = 0;
       for( int i = 1; i <= N; i++ )
       {
           memset( visit , 0 , sizeof( visit ) );
           if( path( i , N ) ) ans++;        
       }
       printf( "%d\n",N - ans/2 );
    }
    //system( "pause" );
    return 0;
}