拓扑排序（）

 1 #include<iostream>
 2 #include<vector>
 3 #include<cstring>
 4 #include<queue>
 5 using namespace std;
 6 #define maxn 500000
 7 vector <int> vc[maxn];
 8 int n, m;
 9 int dis[maxn];
10 bool toupu()
11 {
12     queue<int> q;
13     while (!q.empty()) q.pop();
14     for (int i = 1; i <= n; i++) if (!dis[i]) q.push(i);
15     int ans = 0;
16     while (!q.empty())
17     {
18         int temp = q.front(); q.pop();
19         ans++;
20         for (int i = 0; i < vc[temp].size(); i++)
21         {
22             if (--dis[vc[temp][i] ]== 0) q.push(vc[temp][i]);
23         }
24     }
25     if (ans == n) return true;
26     return false;
27 }
28 int main()
29 {
30     int t;
31     cin >> t;
32     while (t--)
33     {
34         cin >> n >> m;
35         for (int i = 0; i < n; i++) vc[i].clear();
36         memset(dis, 0, sizeof(dis));
37         for (int i = 0; i < m; i++)
38         {
39             int a, b;
40             cin >> a >> b;
41             vc[a].push_back(b);
42             dis[b]++;
43         }
44         if (!toupu()) cout << "Wrong" << endl;
45         else cout << "Correct" << endl;
46     }
47     return 0;
48 }