加权有向图----加权有向图的实现

public class DirectedEdge {
	private int v;
	private int w;
	private double weight;
	
	public DirectedEdge(int v,int w,double weight) {
		this.v = v;this.w = w;this.weight = weight;
	}
	public double weight(){  return weight;  }
	public int form(){  return v;  }
	public int to(){  return w;  }
    public String toString(){  return String.format("%d->%d %.2f", v,w,weight);  }
}

public class EdgeWeightedDigraph {
	private int V;//顶点数
	private int E;//边数
	private Bag<DirectedEdge>[] adj;//邻接表
	public EdgeWeightedDigraph(int V) {
		this.V = V;
		this.E = 0;
		adj = (Bag<DirectedEdge>[]) new Bag[V];
		for(int v=0;v< V;v++) {
			adj[v] = new Bag<DirectedEdge>();
		}
	}
	public int V() {return V;}
	public int E() {return E;}
	
	public void addEdge(DirectedEdge e) {
		adj[e.form()].add(e);
		E++;
	}
    //从v指出的边
	public Iterable<DirectedEdge> adj(int v){return adj[v];}
    //该有向图中所有的边
	public Iterable<DirectedEdge> edges(){
		Bag<DirectedEdge> bag = new Bag<DirectedEdge>();
		for(int v = 0; v<V; v++)
			for(DirectedEdge e : adj[v])
				bag.add(e);
		return bag;
	}
}