0pts 求调

代码如下

#include<bits/stdc++.h>
#define I return
#define love 0
#define DLY ;
using namespace std;
const int maxn=5e5+10;
const int maxm=2e6+10;
int head[maxn],ver[maxm],nxt[maxm],tot=-1;
int dfn[maxn],low[maxn],bridge[maxn];
int times;
int id[maxn],dcc=1;
int v[maxn];
void tarjan(int x,int edge)
{
    dfn[x]=low[x]=times++;
    for (int i=head[x];i;nxt[i])
    {
        int y=ver[i];
        if (!dfn[y])
        {
            tarjan(x,i);
            low[x]=min(low[x],low[y]);
            if (dfn[x]<low[x])
            {
                bridge[i]=bridge[i^1]=1;
            }
        }
        else if(i!=(edge^1))
        {
            low[x]=min(low[x],dfn[y]);
        }
    }
}
void dfs(int x)
{
    id[x]=dcc;
    for (int i=head[x];i;nxt[i])
    {
        int y=ver[i];
        if (id[y]||bridge[i]){continue;}
        dfs(y);
    }
}
void add(int x,int y)
{
    ver[++tot]=y,nxt[tot]=head[x],head[x]=tot;
}
int main()
{
    int n,m;
    cin>>n>>m;
    for(int i=0;i<m;i++)
    {
        int u,v;
        cin>>u>>v;
        add(u,v);
        add(v,u);
    }
    for (int i=0;i<n;++i)
    {
        if (!dfn[i])
        {
            tarjan(i,0);
        }
    }
    for (int i=0;i<n;++i)
    {
        if (!id[i])
        {
            dcc++;
            dfs(i);
        }
    }
    cout<<dcc<<endl;
    for (int i=1;i<=dcc;++i)
    {
        for (int j=0;j<=tot;j+=2)
        {
            int x=ver[j],y=ver[j^1];
            if (id[y]==j&&id[x]==j&&!v[x]&&!v[y]){cout<<x<<' '<<y;v[x]=v[y]=1;}
        }
        cout<<endl;
    }
    I love DLY
}