48分求调

#include<bits/stdc++.h>
using namespace std;
int n,m;
vector<pair<int,int> >p[650000];
int vik[650000],dfn[650000];
int low[650000],ans,d,kk,vis[650000];
vector<int>pp[650000];
stack<int>xp;
void dfs(int x,int dd){
//	cout<<x<<" ";
	xp.push(x);
	d++;
	dfn[x]=low[x]=d;
	for(int i=0;i<p[x].size();i++){
		if(p[x][i].second==dd){
			continue;
		}
		if(dfn[p[x][i].first]!=0){
			low[x]=min(dfn[p[x][i].first],low[x]);
		}
		else{
			dfs(p[x][i].first,p[x][i].second);
			low[x]=min(low[x],low[p[x][i].first]);
			if(low[p[x][i].first]>=dfn[x]){
				ans++;
				while(xp.top()!=x&&xp.size()){
					pp[ans].push_back(xp.top());
					xp.pop();
				}
				pp[ans].push_back(x);
			}
		}
	}
}
int main(){
	cin>>n>>m;
	for(int i=0;i<m;i++){
		int x,y;
		cin>>x>>y;
		if(x==y){
			continue;
		}
		p[x].push_back({y,i});
		p[y].push_back({x,i});
	}
	for(int i=1;i<=n;i++){
		if(dfn[i]==0){
			while(xp.size()!=0){
				xp.pop();
			}
			dfs(i,-1);
	//		cout<<endl;
		}
	}
	int ank=ans;
	for(int i=1;i<=ans;i++){
		for(int j=0;j<pp[i].size();j++){
			vis[pp[i][j]]=1;
		} 
	} 
	for(int i=1;i<=n;i++){
		if(vis[i]==0){
			ans++;
		}
	}
	cout<<ans<<endl;
	for(int i=1;i<=ank;i++){
		cout<<pp[i].size()<<" ";
		for(int j=0;j<pp[i].size();j++){
			cout<<pp[i][j]<<" ";
		}
		cout<<endl;
	} 
	for(int i=1;i<=n;i++){
		if(vis[i]==0){
			cout<<1<<" "<<i<<endl;
		}
	}
	return 0;
}