Below is the syntax highlighted version of AdjMatrixEdgeWeightedDigraph.java.
/****************************************************************************** * 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 allowed. * ******************************************************************************/ package edu.princeton.cs.algs4; import java.util.Iterator; import java.util.NoSuchElementException; /** * The {@code AdjMatrixEdgeWeightedDigraph} class represents an edge-weighted * digraph of vertices named 0 through <em>V</em> - 1, where each * directed edge is of type {@link DirectedEdge} and has a real-valued weight. * It supports the following two primary operations: add a directed edge * to the digraph and iterate over all of edges incident from a given vertex. * It also provides * methods for returning the number of vertices <em>V</em> and the number * of edges <em>E</em>. Parallel edges are disallowed; self-loops are permitted. * <p> * This implementation uses an adjacency-matrix representation. * All operations take constant time (in the worst case) except * iterating over the edges incident from a given vertex, which takes * time proportional to <em>V</em>. * <p> * For additional documentation, * see <a href="https://algs4.cs.princeton.edu/44sp">Section 4.4</a> of * <i>Algorithms, 4th Edition</i> by Robert Sedgewick and Kevin Wayne. * * @author Robert Sedgewick * @author Kevin Wayne */ public class AdjMatrixEdgeWeightedDigraph { private static final String NEWLINE = System.getProperty("line.separator"); private final int V; private int E; private DirectedEdge[][] adj; /** * Initializes an empty edge-weighted digraph with {@code V} vertices and 0 edges. * @param V the number of vertices * @throws IllegalArgumentException if {@code V < 0} */ public AdjMatrixEdgeWeightedDigraph(int V) { if (V < 0) throw new IllegalArgumentException("number of vertices must be non-negative"); this.V = V; this.E = 0; this.adj = new DirectedEdge[V][V]; } /** * Initializes a random edge-weighted digraph with {@code V} vertices and <em>E</em> edges. * @param V the number of vertices * @param E the number of edges * @throws IllegalArgumentException if {@code V < 0} * @throws IllegalArgumentException if {@code E < 0} */ public AdjMatrixEdgeWeightedDigraph(int V, int E) { this(V); if (E < 0) throw new IllegalArgumentException("number of edges must be non-negative"); if (E > V*V) throw new IllegalArgumentException("too many edges"); // can be inefficient while (this.E != E) { int v = StdRandom.uniformInt(V); int w = StdRandom.uniformInt(V); double weight = 0.01 * StdRandom.uniformInt(0, 100); addEdge(new DirectedEdge(v, w, weight)); } } /** * Returns the number of vertices in the edge-weighted digraph. * @return the number of vertices in the edge-weighted digraph */ public int V() { return V; } /** * Returns the number of edges in the edge-weighted digraph. * @return the number of edges in the edge-weighted digraph */ public int E() { return E; } /** * Adds the directed edge {@code e} to the edge-weighted digraph (if there * is not already an edge with the same endpoints). * @param e the edge */ public void addEdge(DirectedEdge e) { int v = e.from(); int w = e.to(); validateVertex(v); validateVertex(w); if (adj[v][w] == null) { E++; adj[v][w] = e; } } /** * Returns the directed edges incident from vertex {@code v}. * @param v the vertex * @return the directed edges incident from vertex {@code v} as an Iterable * @throws IllegalArgumentException unless {@code 0 <= v < V} */ public Iterable<DirectedEdge> adj(int v) { validateVertex(v); return new AdjIterator(v); } // support iteration over graph vertices private class AdjIterator implements Iterator<DirectedEdge>, Iterable<DirectedEdge> { private int v; private int 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()) { throw new NoSuchElementException(); } return adj[v][w++]; } public void remove() { throw new UnsupportedOperationException(); } } /** * Returns a string representation of the edge-weighted digraph. This method takes * time proportional to <em>V</em><sup>2</sup>. * @return the number of vertices <em>V</em>, followed by the number of edges <em>E</em>, * followed by the <em>V</em> adjacency lists of edges */ public String toString() { 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(); } // throw an IllegalArgumentException unless {@code 0 <= v < V} private void validateVertex(int v) { if (v < 0 || v >= V) throw new IllegalArgumentException("vertex " + v + " is not between 0 and " + (V-1)); } /** * Unit tests the {@code AdjMatrixEdgeWeightedDigraph} data type. * * @param args the command-line arguments */ 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); } } /****************************************************************************** * Copyright 2002-2022, Robert Sedgewick and Kevin Wayne. * * This file is part of algs4.jar, which accompanies the textbook * * Algorithms, 4th edition by Robert Sedgewick and Kevin Wayne, * Addison-Wesley Professional, 2011, ISBN 0-321-57351-X. * http://algs4.cs.princeton.edu * * * algs4.jar is free software: you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation, either version 3 of the License, or * (at your option) any later version. * * algs4.jar is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with algs4.jar. If not, see http://www.gnu.org/licenses. ******************************************************************************/