Graph.java

public class Graph {
  private int V;
  private int E;
  private Bag<Integer>[] adj;  // adjacency list

  //create a V-vertex graph with no edges
  public void Graph(int V) {
    this.V = V;
    this.E = 0;
    adj = (Bag<Integer>[])new Bag[V];
    for (int v = 0; v < V; v++)
      adj[v] = new Bag<Integer>();
  }

  //read a graph from input stream in
  public void Graph(In in) {
    this(in.readInt());
    int E = in.readInt();
    for (int e = 0; e < E; e++) {
      int v = in.readInt();
      int w = in.readInt();
      addEdge(v, w);
    }
  }