import java.util.Iterator;
import java.util.LinkedList;

class Graph {

    private int V;
    private LinkedList<Integer>[] adj;
    Graph(int v) {
        V = v;
        adj = new LinkedList[v];
        for (int i = 0; i < v; ++i)
            adj[i] = new LinkedList<>();
    }
    void addEdge(int u, int v) {
        adj[u].add(v);
    }
    void BFS(int s) {
        boolean vis[] = new boolean[V];
        LinkedList<Integer> queue = new LinkedList<>();
        vis[s] = true;
        queue.add(s);
        while (!queue.isEmpty()) {
            s = queue.poll();
            System.out.print(s + " ");
            Iterator<Integer> i = adj[s].listIterator();
            while (i.hasNext()) {
                int n = i.next();
                if (!vis[n]) {
                    vis[n] = true;
                    queue.add(n);
                }
            }
        }
    }

    public static void main(String args[]) {
        Graph g = new Graph(8);
        g.addEdge(0, 1);
        g.addEdge(3, 2);
        g.addEdge(5, 2);
        g.addEdge(3, 5);
        g.addEdge(3, 4);
        g.addEdge(4, 6);
        g.addEdge(6, 3);
        g.addEdge(6, 7);
        g.addEdge(7, 1);

        System.out.print("BFS traversal from vertex 0 is: ");
        g.BFS(0);
    }
}