cyclic.cpp

#include<iostream>
#include<vector>
using namespace std;

class Graph{
    int V;
    vector<int> *l;
public:
    Graph(int v){
        V = v;
        l = new vector<int>[V];
    }
    void addEdge(int x, int y, bool undir=true){
        l[x].push_back(y);
        if(undir)
            l[y].push_back(x);
    }
    bool dfs(int src, vector<bool> &visted, int parent){
        visted[src]=true;
        for(auto node : l[src]){
            if(!visted[node]){
                bool val = dfs(node, visted, src);
                if(val==true)
                    return true;
            }
            else if(parent!=node)
                return true;

        }
        return false;
    }
};

int main(){
    Graph g(3);
    g.addEdge(0, 1);
    g.addEdge(0, 2);
    vector<bool> visted(3, false);
    cout<<g.dfs(0, visted, -1)<<endl;
}