articulation bridge

#include<bits/stdc++.h>
using namespace std;
#define F first
#define S second
int tim=0;
vector<bool> vis;
vector<int> tin,low;
set<pair<int,int> > ans;
vector<int> adj[100005];
void dfs(int v,int p)
{
    low[v]=tin[v]=tim++;
    vis[v]=1;
    for(auto u:adj[v])
    {
        if(u==p) continue;
        if(vis[u]) low[v]=min(low[v],tin[u]);
        else
        {
            dfs(u,v);
            low[v]=min(low[v],low[u]);
            if(low[u]>tin[v]) ans.insert({min(u,v),max(u,v)});
        }
    }
}
int main()
{
    int n,m;
    cin>>n>>m;
    for(int i=0;i<m;i++)
    {
        int a,b;
        cin>>a>>b;
        adj[a].push_back(b);
        adj[b].push_back(a);
    }
    vis.assign(n+1,0);
    tin.assign(n+1,-1);
    low.assign(n+1,-1);
    for(int i=0;i<n;i++)
    {
        if(!vis[i]) dfs(i,-1);
    }
    for(auto i:ans) cout<<i.F<<' '<<i.S<<endl;
    return 0;
}