#include<bits/stdc++.h>
using namespace std;
class Graph
{
    int V;
    list<int> *adj;
public:
    Graph(int V);
    void addEdge(int u, int v);
    void BFS(int s);
};

Graph::Graph(int V)
{
    this->V=V;
    adj = new list<int>[V];
}

void Graph::addEdge(int u, int v)
{
    adj[u].push_back(v);
}

void Graph::BFS(int s)
{
    bool *visited = new bool[V];
    for(int i=0; i<V; i++)
        visited[i] = false;
    list<int> queue;
    visited[s]=true;
    queue.push_back(s);
    while(!queue.empty())
    {
        s = queue.front();
        cout<<s<<" ";
        queue.pop_front();
        list<int> ::iterator i;
        for(i=adj[s].begin(); i!=adj[s].end(); i++)
        {
            if(!visited[*i])
            {
                visited[*i] = true;
                queue.push_back(*i);
            }
        }
    }
}

int main()
{
    // Create a graph given in the above diagram
    Graph g(4);
    g.addEdge(0, 1);
    g.addEdge(0, 2);
    g.addEdge(1, 2);
    g.addEdge(2, 0);
    g.addEdge(2, 3);
    g.addEdge(3, 3);


    cout << "Following is Breadth First Traversal "
         << "(starting from vertex 2) \n";
    g.BFS(2);

    return 0;
}