调了挺久的

实在是黔驴技穷了，故求助qwq

这里是代码：

#include<bits/stdc++.h>
using namespace std;

const int N=20005;
priority_queue<int,vector<int>,greater<int> > ans;
vector<int> son[N];
int dfn[N],low[N],t=0,root;

void dfs(int u){
	dfn[u]=low[u]=++t;	
	int cnt=0;
	for(int i=0;i<son[u].size();i++){
		int v=son[u][i];
		if(dfn[v]){
			low[u]=min(low[u],dfn[v]);
			continue;
		}
		cnt++;
		dfs(v);
		low[u]=min(low[u],low[v]);
		if(dfn[u]<=low[v])
			if(u!=root || cnt>=2)
				ans.push(u);
	}
}

int main(){
	int n,m,x,y;
	scanf("%d%d",&n,&m);
	for(int i=1;i<=m;i++){
		scanf("%d%d",&x,&y);
		son[x].push_back(y);
		son[y].push_back(x);
	}
	for(int i=1;i<=n;i++)
		if(!dfn[i]){
			root=i;
			dfs(i);
		}	
	printf("%d\n",ans.size());
	while(!ans.empty()){
		printf("%d ",ans.top());
		ans.pop();
	}
	return 0;
}