1 #include 
     
       2  3 using namespace std; 4  5 int graph[101][101]; 6 int kind[101][101];  7 int vis[101]; 8 int pre[101]; 9 int post[101];10 11 int n, m;12 int ans=0;13 int flag;14 int tag;15 16 void dfs(int x)17 {18     pre[x] = ++tag;19     for(int i=1; i<=n; i++)20     {21         if(graph[x][i])22         {23             if(pre[i] == 0)24             {25                 kind[x][i] = 1;26                 dfs(i);27             }            28             else29             {30                 if(post[i] == 0)31                 {32                     kind[x][i] = 3;33                     flag=0;34                 }35                     36                 else if(pre[i] > pre[x])37                     kind[x][i] = 2;38                 else39                     kind[x][i] = 4;40             }41         }42     }43     post[x] = ++tag;44 }45 46 int main()47 {48     int ca;49     while(cin >> n >> m)50     {51         tag=0;52         flag=1;53         memset(graph, 0, sizeof(graph));54         memset(vis, 0, sizeof(vis));55         memset(kind, 0, sizeof(kind));56         for(int i=0; i
      
       > u >> v;60             graph[u][v]=1;61         }62         dfs(1);63         int q;64         cin >> q;65         for(int i=0; i
       
        > u >> v;69             cout << "edge (" << u << "," << v << ") is ";70             if(kind[u][v] == 1)71                 cout << "Tree Edge" << endl;72             if(kind[u][v] == 2)73                 cout << "Down Edge" << endl;74             if(kind[u][v] == 3)75                 cout << "Back Edge" << endl; 76             if(kind[u][v] == 4)77                 cout << "Cross Edge" << endl;78         } 79     }80     return 0;81 }