dfs_for_graph.cpp

//No need of parent node,instead of this we use visited array
#include<bits/stdc++.h>
using namespace std;
const int N=1e5+7;
vector<int>adj[N];
//vector<pair<int,int>>adj[N]  for weighted graph.
bool visited[N];

void dfs(int node){
    visited[node]=true;
//This part is for taking action after entering the vertex.
    for(auto child : adj[node]){
//This part is for taking action on child before entering the child.
        if(visited[child]){
            continue;
        }
        dfs(child);
//Take action on child after exiting the child node.
    }
//Take action on the node before exiting the node.
}

int main(){
    int v,e;
    cin>>v>>e;
    for(int i=0;i<e;i++){
        int a,b;
        cin>>a>>b;
        adj[a].push_back(b);
        adj[b].push_back(a);
        //adj[a].push_back({b,w}); for weighted graph
        //adj[b].push_back({a,w});
    }
    return 0;
}