D01 拓扑排序

#include<bits/stdc++.h>
using namespace std;
const int N=110;
vector<int>G[N],ans;
int n,din[N];
bool toposort()
{
	priority_queue<int,vector<int>,greater<int>>q;
	for(int i=1;i<=n;i++)if(din[i]==0)q.push(i);
	while(!q.empty())
	{
		int x=q.top();q.pop();
		ans.push_back(x);
		for(int y:G[x])
			if( --din[y]==0) q.push(y);
	}
	return ans.size()==n;
}
int main()
{
    while( scanf("%d",&n)!=EOF) 
    {
        memset(G,0,sizeof(G));ans.clear();
        memset(din,0,sizeof(din));
        for(int i=1;i<=n;i++)
        {
            int k;scanf("%d",&k);
            for(int j=1; j<=k; j++)
            {
                int x;scanf("%d",&x);
                G[i].push_back(x);
                din[x]++;
            }
        }
        if( !toposort() ){puts("No answer.");continue;}
        else
        {
            for(int x:ans) printf("%d ",x);
            printf("\n");
        }
    }
    return 0;
}