UVa-10305 Ordering Tasks 

 1 #include <bits/stdc++.h>
 2 
 3 const int maxn = 102;
 4 using namespace std;
 5 
 6 int G[maxn][maxn];
 7 int n,m;
 8 int vis[maxn];
 9 int topo[maxn],tmpN;
10 bool dfs(int u)
11 {
12     vis[u] = -1;//under visting
13     for(int v = 1; v <= n; v ++)
14     {
15         if(G[u][v])
16         {
17             if(vis[v]<0)    return false;//loop
18             else if(!vis[v] && !dfs(v))    return false;
19         }
20     }
21     vis[u] = 1;
22     topo[--tmpN]=u;
23 
24     return true;
25 }
26 
27 bool toposort()
28 {
29     tmpN = n;
30     for(int u = 1; u <= n; u ++)
31     {
32         if(!vis[u])
33             if(!dfs(u))
34                 return false;
35     }
36     return true;
37 }
38 
39 void solve()
40 {
41     if(toposort())
42     {
43         for(int i = 0; i < n; i ++)
44             cout << topo[i] << " ";
45         cout << endl;
46     }
47 }
48 
49 int main()
50 {
51     while(cin >> n >> m)
52     {
53         memset(G,0,sizeof(G));
54         memset(vis,0,sizeof(vis));
55         while(m --)
56         {
57             int tmp1,tmp2;
58             cin >> tmp1 >> tmp2;
59             G[tmp1][tmp2] = 1;
60         }
61         solve();
62     }
63     return 0;
64 }

 

posted @ 2018-11-20 19:34  Asurudo  阅读(140)  评论(0)    收藏  举报