public void addEdge(DirectedEdge e) {
int v = e.from();
int w = e.to();
validateVertex(v);
validateVertex(w);
adj[v].add(e);
E++;
}
public DoublyLinkedList<DirectedEdge> adjacent(int v) {
validateVertex(v);
return adj[v];
}
public Iterable<DirectedEdge> adj(int v) {
validateVertex(v);
return adj[v];
}