xhk2000的专栏

D. Directed Roads time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output ZS the Coder and Chris the Baboon has explored Uday

void tarjan(int u) {     dfn[u]=low[u]=++stamp;     used[u]=1;//进栈     s.push(u);     for(int i=0;i     {         int v=graph[u][i];         if(used[v]==0)         {             tarjan(v);//