HDOJ 1285 拓扑排序 水题

#include<bits/stdc++.h>
#define INF 1e18
#define inf 1e9
#define min(a,b) a<b?a:b
#define max(a,b) a>b?a:b
#define lson l,m,rt<<1
#define rson m+1,r,rt<<1|1
#define IOS ios_base::sync_with_stdio(false),cin.tie(0),cout.tie(0)
using namespace std ;
typedef long long ll;
typedef unsigned long long ull;
const ll _max = 505;
int n,m;
int mp[_max][_max];
int ft[_max];
int ans[_max];
void topsort(){
priority_queue<int,vector<int>,greater<int> > q;
while(!q.empty()) q.pop();
for(int i = 1 ; i <= n ; i++){
if(!ft[i])
q.push(i);
}
int id = 0;
int cnt = 0;
while(!q.empty()){
id = q.top();
q.pop();
ans[cnt++]=id;
for(int i = 1 ; i <= n ; i++){
if(mp[id][i]){
ft[i]--;
if(!ft[i])  q.push(i);
}

}
}
cout<<ans[0];
for(int i = 1 ; i < cnt ; i++)
cout<<" "<<ans[i];
cout<<endl;
return ;
}
int main(){
IOS;
while(cin>>n>>m){
memset(mp,0,sizeof(mp));
memset(ft,0,sizeof(ft));
int u,v;
for(int i = 1 ; i <= m ; i++){
cin>>u>>v;
if(!mp[u][v]){
mp[u][v] = 1;
++ft[v];
}
}
topsort();
}
return 0;
}