graph.java

import java.util.*;

class graph{
  int V;
 LinkedList<Integer> adj[];
  @SuppressWarnings("unchecked")
  graph(int v){
    V=v;
    adj = new LinkedList[v];
    for(int i=0;i<v;i++)
        adj[i] = new LinkedList<Integer>();
  }

  void addEdge(int v,int w){
    adj[v].add(w);
  }
  void bst(int s){
    boolean visited[] = new boolean[V];
    LinkedList<Integer> q = new LinkedList<Integer>();

    visited[s] = true;
    q.add(s);
    while(q.size()!=0){
      s = q.poll();
      System.out.println(s);

      Iterator<Integer> i = adj[s].listIterator();
      while(i.hasNext()){
        int n = i.next();
        if(!visited[n]) {
          visited[n] = true;
          q.add(n);
        }
      }
    }
  }
  public static void main(String[] args){
      graph g = new graph(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);

        g.bst(0);
  }

}