001package algs44;
002import  stdlib.*;
003import java.util.Iterator;
004import java.util.NoSuchElementException;
005
006/* ***********************************************************************
007 *  Compilation:  javac AdjMatrixEdgeWeightedDigraph.java
008 *  Execution:    java AdjMatrixEdgeWeightedDigraph V E
009 *  Dependencies: StdOut.java
010 *
011 *  An edge-weighted digraph, implemented using an adjacency matrix.
012 *  Parallel edges are disallowed; self-loops are allowd.
013 *
014 *************************************************************************/
015
016public class AdjMatrixEdgeWeightedDigraph {
017        private int V;
018        private int E;
019        private DirectedEdge[][] adj;
020
021        // empty graph with V vertices
022        public AdjMatrixEdgeWeightedDigraph(int V) {
023                if (V < 0) throw new RuntimeException("Number of vertices must be nonnegative");
024                this.V = V;
025                this.E = 0;
026                this.adj = new DirectedEdge[V][V];
027        }
028
029        // random graph with V vertices and E edges
030        public AdjMatrixEdgeWeightedDigraph(int V, int E) {
031                this(V);
032                if (E < 0) throw new RuntimeException("Number of edges must be nonnegative");
033                if (E > V*V) throw new RuntimeException("Too many edges");
034
035                // can be inefficient
036                while (this.E != E) {
037                        int v = (int) (V * Math.random());
038                        int w = (int) (V * Math.random());
039                        double weight = Math.round(100 * Math.random()) / 100.0;
040                        addEdge(new DirectedEdge(v, w, weight));
041                }
042        }
043
044        // number of vertices and edges
045        public int V() { return V; }
046        public int E() { return E; }
047
048
049        // add directed edge v->w
050        public void addEdge(DirectedEdge e) {
051                int v = e.from();
052                int w = e.to();
053                if (adj[v][w] == null) {
054                        E++;
055                        adj[v][w] = e;
056                }
057        }
058
059        // return list of neighbors of v
060        public Iterable<DirectedEdge> adj(int v) {
061                return new AdjIterator(v);
062        }
063
064        // support iteration over graph vertices
065        private class AdjIterator implements Iterator<DirectedEdge>, Iterable<DirectedEdge> {
066                private int v, w = 0;
067                public AdjIterator(int v) { this.v = v; }
068
069                public Iterator<DirectedEdge> iterator() { return this; }
070
071                public boolean hasNext() {
072                        while (w < V) {
073                                if (adj[v][w] != null) return true;
074                                w++;
075                        }
076                        return false;
077                }
078
079                public DirectedEdge next() {
080                        if (hasNext()) { return adj[v][w++];                 }
081                        else           { throw new NoSuchElementException(); }
082                }
083
084                public void remove()  { throw new UnsupportedOperationException();  }
085        }
086
087
088        // string representation of Graph - takes quadratic time
089        public String toString() {
090                String NEWLINE = System.getProperty("line.separator");
091                StringBuilder s = new StringBuilder();
092                s.append(V + " " + E + NEWLINE);
093                for (int v = 0; v < V; v++) {
094                        s.append(v + ": ");
095                        for (DirectedEdge e : adj(v)) {
096                                s.append(e + "  ");
097                        }
098                        s.append(NEWLINE);
099                }
100                return s.toString();
101        }
102
103
104        // test client
105        public static void main(String[] args) {
106                int V = Integer.parseInt(args[0]);
107                int E = Integer.parseInt(args[1]);
108                AdjMatrixEdgeWeightedDigraph G = new AdjMatrixEdgeWeightedDigraph(V, E);
109                StdOut.println(G);
110        }
111
112}