看了别人博客  http://blog.csdn.net/jokes000/article/details/7538994

 

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              #define CL(a,b) memset(a,b,sizeof(a))#define ll __int64#define TEST cout<<"TEST ***"<
              

st;int head[10010],ct,tim;int ti[10010],lo[10010],ins[10010],n,m;void inithead(){ CL(head,-1); tim=0; ct=0;}void addedge(int s,int e){ edge[ct].e=e;edge[ct].next=head[s];head[s]=ct++;}void targan(int i){ tim++; ti[i]=tim;lo[i]=tim; st.push(i); ins[i]=1; int p=head[i]; int v; while(p!=-1) { v=edge[p].e; if(ins[v]==1) { lo[i]=min(lo[v],lo[i]); } else if(ti[v]==0) { targan(v); lo[i]=min(lo[i],lo[v]); } p=edge[p].next; } if(lo[i]==ti[i]) { while(!st.empty()&&lo[st.top()]==ti[i]) { ins[st.top()]=0; st.pop(); } }}int main(){ while(scanf("%d %d",&n,&m)!=EOF) { if(n==0&&m==0)break; int i,j,a,b; inithead(); CL(lo,0); CL(ti,0); CL(ins,0); for(i=0;i