BestCoder Round #1

#include<iostream>
#include<cstdio>
#include<cstring>
#include<vector>
#include<queue>
#include<algorithm>
#define MAXN  30005
using namespace std;
vector<int> g[MAXN];
int in[MAXN];
int n;
void clear()
{
    for(int i=1; i<=n; ++i)
    {
        g[i].clear();
        in[i]=0;
    }
}
int main()
{
    int T;
    scanf("%d",&T);
    while(T--)
    {
        int m;
        scanf("%d%d",&n,&m);
        clear();
        while(m--)
        {
            int a,b;
            scanf("%d%d",&a,&b);
            g[b].push_back(a);
            in[a]++;
        }
        priority_queue<int,vector<int>,less<int> > pq;
        for(int i=1; i<=n; ++i)
            if(in[i]==0)
                pq.push(i);
        vector<int> ans;
        while(!pq.empty())
        {
            int p=pq.top();
            pq.pop();
            ans.push_back(p);
            for(int i=0; i<g[p].size(); ++i)
            {
                int &u=g[p][i];
                in[u]--;
                if(!in[u]) pq.push(u);
            }
        }
        for(int i=ans.size()-1; i>=0; --i)
            if(i==ans.size()-1) printf("%d",ans[i]);
            else printf(" %d",ans[i]);
        printf("\n");
    }
    return 0;
}