POJ 1274 The Perfect Stall （匈牙利算法）

题意：一同牛只愿意在几个特定的棚子里面产奶。每头牛喜好不同，每个棚子只容纳一同牛。求最大匹配。
#include <iostream>
using namespace std;

#define N 210
bool vis
, bond

;
int match
;
int n, m;

bool find_path ( int u )
{
for ( int v = 1; v <= m; v++ )
{
if ( bond[u][v] && !vis[v] )
{
vis[v] = true;
/* 若从match[v]出发找不到增广路径，那么无论再从别的点出发找到多少增广路径来改变现在的匹配，从match[u]出发都永远找不到增广路径。*/
if ( !match[v] || find_path(match[v]) )
{
match[v] = u;
return true;
}
}
}
return false;
}

int Hungary ()
{
int i, ans = 0;
memset(match,0,sizeof(match));
for ( i = 1; i <= n; i++ )
{
memset(vis,0,sizeof(vis));
if ( find_path ( i ) )
ans++;
}
return ans;
}

int main()
{
int num, s, i, j;
while ( scanf("%d %d",&n,&m) != EOF )
{
memset(bond,0,sizeof(bond));

for ( i = 1; i <= n; i++ )
{
scanf("%d",&num);
for ( j = 1; j <= num; j++ )
{
scanf("%d",&s);
bond[i][s] = true;
}
}
printf("%d\n",Hungary());
}
return 0;
}