POJ 1469 二分图最大匹配

思路：裸的二分图最大匹配，居然没看出来，我还是要学习一个

#include<cstdio>
#include<iostream>
#include<cstring>
#include<algorithm>
#include<cmath>
#include<cstdlib>
#include<sstream>
#include<iomanip>
using namespace std;
const int MOD = 1e9 + 7;

typedef long long LL;
typedef unsigned long long ULL;

const int maxn = 300 + 5;
bool g[maxn][maxn];
int link[maxn];
bool check[maxn];

int n,m,k;
bool dfs(int u){
   for(int i = 1; i <= m; ++i){
       if(!check[i] && g[u][i]){
           check[i] = true;
           if(link[i] == -1 || dfs(link[i])){
                link[i] = u;
                return true;
           }
       }
   }
   return false;
}

int hugarian(){
   int ans = 0;
   memset(link,-1,sizeof(link));
   for(int i = 1; i <= n; ++i){
      memset(check,0,sizeof(check));
      if(dfs(i))
         ++ans;
   }
   return ans ;
}

int main(){
   int t;
   scanf("%d",&t);
   while(t--){
       memset(g,0,sizeof(g));
       scanf("%d%d",&n,&m);
       for(int i = 1; i <= n; ++i){
          int d;
          scanf("%d",&d);
          for(int j = 0; j < d; ++j){
              int x;
              scanf("%d",&x);
              g[i][x] = 1;
          }
       }
       int num = hugarian();
       if(num == n){
           printf("YES
");
       }
       else printf("NO
");
   }
   return 0;
}