拓扑排序

#include<iostream>
#include<queue>
#include<vector>
#include<cstring>
using namespace std;
int n,m,x,y,in[30001];
priority_queue<int>q,*pq;
queue<int>ans;
vector<int>l[30001];
void init(){
    pq=new priority_queue<int>();
    q=(*pq);
    memset(l,0,sizeof(l));
    memset(in,0,sizeof(in));
}
void bfs(){
    while(!q.empty()){
        int v=q.top();
        q.pop();
        ans.push(v);
        for(int i=0;i<l[v].size();i++){
            int u=l[v][i];
            in[u]--;
            if(!in[u])q.push(u);
        }
    }
}
void out(){
	if(ans.empty())return ;
	int v=ans.front();
	ans.pop();
	out();
	cout<<v<<" ";
}
int main(){
    int t;
    cin>>t;
    while(t--){
        cin>>n>>m;
        init();
        for(int i=1;i<=m;i++){
            cin>>x>>y;
            l[y].push_back(x);
            in[x]++;
        }
        for(int i=1;i<=n;i++)if(!in[i])q.push(i);
        bfs();
        out();
        cout<<endl;
    }
}
/*
1
5 10
3 5
1 4
2 5
1 2
3 4
1 4
2 3
1 5
3 5
1 2
*/