bridges.cpp

#include<bits/stc++.h>
#include<iostream>
#include<algorithm>
#include<vector>

using namespace std;

void dfs(int node, int parent, vector<int> &vis, vector<int> &tin, vector<int> &low, int &timer, vector<int> adj[]){
    vis[node]=1;
    tin[node]=low[node]=timer++;
    for(auto it:adj[node]){
        if(it==parent)
          continue;
        
        if(!vis[it]){
            dfs(it, node, vis, tin, low, timer, adj);
            low[node]=min(low[node], low[it]);
            if(low[it]> tin[node]){
                cout<<node<<" "<<it<<endl;
            }
        }
        else{
            low[node]=min(low[node], tin[it]);
        }
    }   
}


int main(){
    int n,m;
    cin>>n>>m;
    vector<int> adj[n];
    for(int i=0;i<m;i++){
        int u,v;
        cin>>u>>v;
        adj[u].push_back(v);
        adj[v].push_back(u);

    }

    vector<int> vis(n,0);
    vector<int> tin(n,-1);
    vector<int> low(n,-1);

    int timer=0;
    for(int i=0;i<n;i++){
        if(!vis[i]){
            dfs(i, -1, vis, tin, low, timer, adj);
        }
    }
     return 0;
}