求点双联通分量(HihoCoder

#include<cstdio>
#include<algorithm>
#include<cstring>
#include<stack>
using namespace std;

struct my{
  int v;
  int next;
  int id;
};

my bian[2000000+10];
int adj[200000+10];
int maxn=(1<<29);
int sccno[200000+10];
int belong[200000+10];
int pre[200000+10];
int bccnum;
int dfsnum;
int fa1;
int n,m;
stack<int>q;

void myinsert(int u,int v,int id){
     bian[++fa1].v=v;
     bian[fa1].next=adj[u];
     adj[u]=fa1;
     bian[fa1].id=id;
}

int tarjan(int u,int fa){
     int lowu=pre[u]=++dfsnum;
     for (int i=adj[u];i!=-1;i=bian[i].next){
        int v=bian[i].v;
        int e=bian[i].id;
        if(belong[e]) continue;
        if(!pre[v]){
            q.push(e);
            int lowv=tarjan(v,u);
            lowu=min(lowv,lowu);
            if(lowv>=pre[u]){
              bccnum++;
              int no=maxn;
              for (;;){
                int e2=q.top();
                q.pop();
                belong[e2]=bccnum;
                no=min(no,e2);
                if(e2==e||q.empty()) break;
              }
              sccno[bccnum]=no;
              }
            } else if(v!=fa&&pre[v]<pre[u]){
                q.push(e);
                lowu=min(lowu,pre[v]);
        }
     }
     return lowu;
}
int main(){
    memset(bian,-1,sizeof(bian));
    memset(adj,-1,sizeof(adj));
    scanf("%d%d",&n,&m);
    int u,v;
    for (int i=1;i<=m;i++){
        scanf("%d%d",&u,&v);
        myinsert(u,v,i);
        myinsert(v,u,i);
    }
    /*for (int i=1;i<=n;i++){
        printf("%d ",i);
        for (int j=adj[i];j!=-1;j=bian[j].next){
            printf("%d ",bian[j].v);
        }
        printf(" ");
    }*/
    tarjan(1,-1);
    printf("%d ",bccnum);
    for (int i=1;i<=m;i++){
            int id=belong[i];
        printf("%d ",sccno[id]);
    }
   printf(" ");
return 0;
}