学步园

#include <stdio.h>
#include <string.h>
#define M 311
int m,n;
int map[M][M], match[M], chk[M];
int find(int p)
{
    int i;
    for(i=1;i<=n;i++)
        if( map[p][i] && chk[i]==0 )
        {
            chk[i]=1;
            if( match[i]==0 || find( match[i] ) )
            {
                match[i]=p;
                return 1;
            }
        }
    return 0;
}

int solve()
{
    int i,res;
    for(i=1,res=0; i<=m; i++)
    {
        memset(chk,0,sizeof(chk));
        res+=find(i);
    }
    return res;
}

int main()
{
    // freopen("in","r",stdin);
    // freopen("out","w",stdout);
    int k,i,x,t,r;
    scanf("%d",&t);
    while( t-- )
    {
        scanf("%d%d",&m,&n);
        memset(map,0,sizeof(map));
        memset(match,0,sizeof(match));
        for(i=1;i<=m;i++)
        {
        	scanf("%d",&k);
        	for(r=0;r<k;r++)
        	{
        		scanf("%d",&x);
        		map[i][x]=1;
        	}
        }
        if( solve()==m )
        	printf("YES\n");
        else
        	printf("NO\n");
    }
    return 0;
}