// Copyright 2003, Trustees of Indiana University
// Please see the license in the file ../LICENSE

import java.util.*;
import java.lang.Integer;

public class adjacency_list 
  implements VertexListAndIncidenceAndEdgeListGraph<
    Integer,
    adj_list_edge<Integer>,
    Iterator<Integer>,
    Iterator<adj_list_edge<Integer>>,
    Iterator<adj_list_edge<Integer>>> {

  public adjacency_list() {
    vertices_ = new ArrayList<Integer>();
    edges_ = new HashMap<Integer, ArrayList<adj_list_edge<Integer>>>();
    all_edges_ = new ArrayList<adj_list_edge<Integer>>();
  }

  private ArrayList<Integer> vertices_;
  public Iterator<Integer> vertices() {
    return vertices_.iterator();
  }
  public int num_vertices() {
    return vertices_.size();
  }

  private HashMap<Integer, ArrayList<adj_list_edge<Integer>>> edges_;
  private ArrayList<adj_list_edge<Integer>> all_edges_;

  public Iterator<adj_list_edge<Integer>> out_edges(Integer v) {
    return edges_.get(v).iterator();
  }
  public int out_degree(Integer v) {
    return edges_.get(v).size();
  }

  public void add_vertex(Integer v) {
    vertices_.add(v);
    edges_.put(v, new ArrayList<adj_list_edge<Integer>>());
  }

  public void add_edge(Integer u, Integer v) {
    adj_list_edge<Integer> edge = new adj_list_edge<Integer>(u,v);
    edges_.get(u).add(edge);
    all_edges_.add(edge);
  }

  public Iterator<adj_list_edge<Integer>> edges() {
    return all_edges_.iterator();
  }
}