有条闭关

#include<bits/stdc++.h>
using namespace std;
int n,ru[505],pq;
bool a[501][501];
int main(){
    cin>>n;
    for(int i=1;i<=n;++i){
        int ii,k,p=1,m;
        cin>>ii>>m;
        while(p<=m&&cin>>k){
            a[ii][k]=1;ru[k]++;++p;
        }
    }
    queue<int> q;
    for(int i=1;i<=n;++i){
        if(ru[i]==0)q.push(i);
    }
    while(!q.empty()){
        int g=q.front();++pq;q.pop();
        for(int i=1;i<=n;++i){
            if(a[g][i]){
                ru[i]--;
            if(!ru[i])q.push(i);}
        }
    }if(n-pq==0)puts("YES");
    else cout<<n-pq;
    return 0;
}