题解：无
代码：
1 #include<cstdio> 2 #include<iostream> 3 #include<cstring> 4 #define max(a,b) ((a)>(b)?(a):(b)) 5 #define min(a,b) ((a)<(b)?(a):(b)) 6 using namespace std; 7 const int maxn=20000,maxm=1e5; 8 int N,M,num_edge=0,edge_head[maxn+50],u,v,DFN[maxn+50],LOW[maxn+50]; 9 int ix=0,son,g[maxn+50],ans=0; 10 struct Edge{ 11 int to,nx; 12 }edge[maxm*2+50]; 13 inline void Add_edge(int from,int to){ 14 edge[++num_edge].nx=edge_head[from]; 15 edge[num_edge].to=to; 16 edge_head[from]=num_edge; 17 return; 18 } 19 void Tarjan(int x,int fa){ 20 DFN[x]=LOW[x]=++ix; 21 for(int i=edge_head[x];i;i=edge[i].nx){ 22 int y=edge[i].to; 23 if(fa!=y){ 24 if(DFN[y]==0){ 25 if(fa==0)son++; 26 Tarjan(y,x); 27 LOW[x]=min(LOW[x],LOW[y]); 28 if(fa!=0&&DFN[x]<=LOW[y]&&g[x]==0){ 29 g[x]=1; 30 ans++; 31 } 32 } 33 else LOW[x]=min(LOW[x],DFN[y]); 34 } 35 } 36 return; 37 } 38 int main(){ 39 scanf("%d%d",&N,&M); 40 for(int i=1;i<=M;i++){ 41 scanf("%d%d",&u,&v); 42 Add_edge(u,v); 43 Add_edge(v,u); 44 } 45 for(int i=1;i<=N;i++) 46 if(DFN[i]==0){ 47 son=0; 48 Tarjan(i,0); 49 if(son>1&&g[i]==0){ 50 g[i]=1; 51 ans++; 52 } 53 } 54 printf("%d ",ans); 55 for(int i=1;i<=N;i++)if(g[i])printf("%d ",i); 56 return 0; 57 }
By:AlenaNuna