HDU 2063 过山车

这是一道裸的二分匹配题：

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