Tarjan求割点 || Luogu P3388 【模板】割点（割顶）

题面：P3388 【模板】割点（割顶）

题解：无

代码：

 #include<cstdio>
 #include<iostream>
 #include<cstring>
 #define max(a,b) ((a)>(b)?(a):(b))
 #define min(a,b) ((a)<(b)?(a):(b))
 using namespace std;
 const int maxn=,maxm=1e5;
 int N,M,num_edge=,edge_head[maxn+],u,v,DFN[maxn+],LOW[maxn+];
 int ix=,son,g[maxn+],ans=;
 struct Edge{
     int to,nx;
 }edge[maxm*+];
 inline void Add_edge(int from,int to){
     edge[++num_edge].nx=edge_head[from];
     edge[num_edge].to=to;
     edge_head[from]=num_edge;
     return;
 }
 void Tarjan(int x,int fa){
     DFN[x]=LOW[x]=++ix;
     for(int i=edge_head[x];i;i=edge[i].nx){
         int y=edge[i].to;
         if(fa!=y){
             if(DFN[y]==){
                 if(fa==)son++;
                 Tarjan(y,x);
                 LOW[x]=min(LOW[x],LOW[y]);
                 if(fa!=&&DFN[x]<=LOW[y]&&g[x]==){
                     g[x]=;
                     ans++;
                 }
             }
             else LOW[x]=min(LOW[x],DFN[y]);
         }
     }
     return;
 }
 int main(){
     scanf("%d%d",&N,&M);
     for(int i=;i<=M;i++){
         scanf("%d%d",&u,&v);
         Add_edge(u,v);
         Add_edge(v,u);
     }
     for(int i=;i<=N;i++)
         if(DFN[i]==){
             son=;
             Tarjan(i,);
             if(son>&&g[i]==){
                 g[i]=;
                 ans++;
             }
         }
     printf("%d\n",ans);
     for(int i=;i<=N;i++)if(g[i])printf("%d ",i);
     return ;
 }

---

By:AlenaNuna