rt

评测记录

#include<bits/stdc++.h>
using namespace std;
#define endl '\n'
const int N=2e5+15;
struct edge{
    int to,next;
}e[N<<1];
int head[N],low[N],dfn[N],n,m,dcccnt,dfncnt;
bool cut[N];
void addedge(int u,int v){
    static int cnt=1;
    e[cnt]={v,head[u]};
    head[u]=cnt++;
}
stack<int>st;
vector<int>dcc[N];
void Tarjan(int u,int root){
    low[u]=dfn[u]=++dfncnt;
    st.push(u);
    if(u==root&&!head[u]){
        dcc[++dcccnt].push_back(u);
        return;
    }
    int f=0;
    for(int i=head[u];i;i=e[i].next){
        int to=e[i].to;
        if(!dfn[to]){
            Tarjan(to,root);
            low[u]=min(low[u],low[to]);
            if(low[to]>=dfn[u]){
                dcccnt++;
                int x;
                do{
                    x=st.top();
                    dcc[dcccnt].push_back(x);
                    st.pop();
                }while(x!=to);
                dcc[dcccnt].push_back(u);
            }
        }
        else low[u]=min(low[u],dfn[to]);
    }
}
signed main(){
    cin>>n>>m;
    for(int i=1;i<=m;i++){
        int u,v;
        cin>>u>>v;
        addedge(u,v);
        addedge(v,u);
    }
    for(int i=1;i<=n;i++){
        if(!dfn[i]){
            Tarjan(i,i);
        }
    }
    cout<<dcccnt<<endl;
    for(int i=1;i<=dcccnt;i++){
        cout<<dcc[i].size()<<' ';
        for(auto p:dcc[i]){
            cout<<p<<' ';
        }
        cout<<endl;
    }
    return 0;
}