/*************************************************************************
 *  Compilation:  javac AdjMatrixEdgeWeightedDigraph.java
 *  Execution:    java AdjMatrixEdgeWeightedDigraph V E
 *  Dependencies: StdOut.java
 *
 *  An edge-weighted digraph, implemented using an adjacency matrix.
 *  Parallel edges are disallowed; self-loops are allowd.
 *  
 *************************************************************************/

import java.util.Iterator;
import java.util.NoSuchElementException;


public class AdjMatrixEdgeWeightedDigraph {
    private int V;
    private int E;
    private DirectedEdge[][] adj;
    
    // empty graph with V vertices
    public AdjMatrixEdgeWeightedDigraph(int V) {
        if (V < 0) throw new RuntimeException("Number of vertices must be nonnegative");
        this.V = V;
        this.E = 0;
        this.adj = new DirectedEdge[V][V];
    }

    // random graph with V vertices and E edges
    public AdjMatrixEdgeWeightedDigraph(int V, int E) {
        this(V);
        if (E < 0) throw new RuntimeException("Number of edges must be nonnegative");
        if (E > V*V) throw new RuntimeException("Too many edges");

        // can be inefficient
        while (this.E != E) {
            int v = (int) (V * Math.random());
            int w = (int) (V * Math.random());
            double weight = Math.round(100 * Math.random()) / 100.0;
            addEdge(new DirectedEdge(v, w, weight));
        }
    }

    // number of vertices and edges
    public int V() { return V; }
    public int E() { return E; }


    // add directed edge v->w
    public void addEdge(DirectedEdge e) {
        int v = e.from();
        int w = e.to();
        if (adj[v][w] == null) {
            E++;
            adj[v][w] = e;
        }
    }

    // return list of neighbors of v
    public Iterable<DirectedEdge> adj(int v) {
        return new AdjIterator(v);
    }

    // support iteration over graph vertices
    private class AdjIterator implements Iterator<DirectedEdge>, Iterable<DirectedEdge> {
        private int v, w = 0;
        public AdjIterator(int v) { this.v = v; }

        public Iterator<DirectedEdge> iterator() { return this; }

        public boolean hasNext() {
            while (w < V) {
                if (adj[v][w] != null) return true;
                w++;
            }
            return false;
        }

        public DirectedEdge next() {
            if (hasNext()) { return adj[v][w++];                 }
            else           { throw new NoSuchElementException(); }
        }

        public void remove()  { throw new UnsupportedOperationException();  }
    }


    // string representation of Graph - takes quadratic time
    public String toString() {
        String NEWLINE = System.getProperty("line.separator");
        StringBuilder s = new StringBuilder();
        s.append(V + " " + E + NEWLINE);
        for (int v = 0; v < V; v++) {
            s.append(v + ": ");
            for (DirectedEdge e : adj(v)) {
                s.append(e + "  ");
            }
            s.append(NEWLINE);
        }
        return s.toString();
    }


    // test client
    public static void main(String[] args) {
        int V = Integer.parseInt(args[0]);
        int E = Integer.parseInt(args[1]);
        AdjMatrixEdgeWeightedDigraph G = new AdjMatrixEdgeWeightedDigraph(V, E);
        StdOut.println(G);
    }

}