1 #include<iostream>
2 #include<cstdio>
3 using namespace std;
4 int n,m,idx,cnt,total;
5 int first[200010],next[200010],to[200010],dfn[100010],low[100010];
6 bool cut[100010];
7 void add (int x,int y)
8 {
9 to[++cnt]=y;
10 next[cnt]=first[x];
11 first[x]=cnt;//加点，记得反向存图
12 }
13 void tarjan (int u,int fa)
14 {
15 dfn[u]=low[u]=++idx;//修改时间戳和low值
16 int child=0;
17 for (int i=first[u];i!=-1;i=next[i])
18 {
19 int nx=to[i];
20 if (dfn[nx]==0)
21 {
22 tarjan (nx,fa);
23 low[u]=min (low[u],low[nx]);
24 if (low[nx]>=dfn[u]&&u!=fa)//是根节点单独讨论
25 cut[u]=1;
26 if(u==fa)
27 child++;
28 }
29 else
30 low[u]=min (low[u],dfn[nx]);
31 }
32 if (child>=2&&u==fa)
33 cut[u]=1;
34 }
35 int main()
36 {
37 scanf ("%d%d",&n,&m);
38 for(int i=1;i<=m;i++)
39 {
40 next[i]=-1;
41 }
42 for(int i=1;i<=n;i++)
43 {
44 first[i]=-1;
45 }
46 for (int i=1;i<=m;i++)
47 {
48 int a,b;
49 scanf ("%d%d",&a,&b);
50 add (a,b);
51 add (b,a);
52 }
53 for (int i=1;i<=n;i++)
54 if (dfn[i]==0)
55 tarjan (i,i);
56 for (int i=1;i<=n;i++)
57 if (cut[i]==1)
58 total++;
59 printf ("%d\n",total);
60 for (int i=1;i<=n;i++)
61 if (cut[i]==1)
62 printf ("%d ",i);
63 return 0;
64 }
2019-09-08 By十四日的夏
