ACM template - topological sorting

temporarily

 1 bool topo()
 2         {
 3             int count = 0 ;
 4             while (!q.empty())
 5                 q.pop();
 6             for (int i = 1; i <= n; i++)
 7                 if (!in[i])
 8                     q.push(i);
 9             while (!q.empty())
10             {
11                 int begin = q.front() ;
12                 q.pop();
13                 count ++ ;
14                 for (int i = 0; i < course[begin].size(); i ++)
15                     if (--in[course[begin][i]]==0)
16                         q.push(course[begin][i]) ;
17             }
18             if(count == n)
19                 return true;
20             else
21                 return false;
22         }