强连通分量模板

                        #include 
                        #include 
                        #include 
                        #include 
                        #include 
                        #include 
                        #include 
                        #include 
                        #define LL long long
                        using namespace std;
                        const int inf=0x3f3f3f3f;
                        const double eps=10e-10;
                        const int maxn=100+2;
                        const int maxm=100*100+2;
                        struct Edge { int v,next; };
                        Edge e[maxm];
                        int head[maxn],tot,dfs_clock,tot2,sccno[maxn],in[maxn],out[maxn],pre[maxn];
                        vector scc_block[maxn];
                        int n;
                        stack S;
                        void addedge(int u,int v)
                        {
                            e[tot].v=v; e[tot].next=head[u];
                            head[u]=tot++;
                        }
                        int find_scc(int u)
                        {
                           int lowu;
                            pre[u]=lowu=++dfs_clock;
                            S.push(u);
                            int i,tem;
                            for(i=head[u];i!=-1;i=e[i].next)
                            {
                                int v=e[i].v;
                                if(!pre[v])
                                {
                                    int lowv=find_scc(v);
                                    lowu=min(lowu,lowv);
                                }
                                else if(!sccno[v])
                                    lowu=min(lowu,pre[v]);
                            }
                            if(lowu==pre[u])
                            {
                                ++tot2;
                                for(;;)
                                {
                                    tem=S.top(); S.pop();
                                    scc_block[tot2].push_back(tem);
                                    sccno[tem]=tot2;
                                    if(tem==u) break;
                                }
                            }
                            return lowu;
                        }
                        int main()
                        {
                            cin>>n;
                            int i,j,tem;
                            tot=0;
                            memset(head,-1,sizeof(head));
                            for(i=1;i<=n;i++)
                                while(scanf("%d",&tem)&&tem) addedge(i,tem);
                            tot2=0;
                            for(i=1;i<=n;i++) if(!pre[i])
                            {
                                dfs_clock=0;
                                find_scc(i);
                            }
                            for(i=1;i<=tot2;i++) in[i]=out[i]=1;
                            int v;
                            for(i=1;i<=n;i++)
                            {
                                for(j=head[i];j!=-1;j=e[j].next)
                                {
                                    v=e[j].v;
                                    if(sccno[i]!=sccno[v]) in[sccno[v]]=out[sccno[i]]=0;
                                }
                            }
                            int in0=0,out0=0;
                            int ans1=0,ans2=0;
                            for(i=1;i<=tot2;i++)
                            {
                                if(in[i]) { in0++; ans1++; }
                                if(out[i]) out0++;
                            }
                            if(tot2==1) ans2=0;
                            else ans2=max(in0,out0);
                            printf("%d\n",ans1);
                            printf("%d\n",ans2);
                            return 0;
                        }