EdgeWeightedDigraph.java

/*
    @EdgeWeightedDigraph LP2
    @author Rui Moreira, Christophe Soares, Ana Ribeiro Gomes
    @Tiago Martins 24440, Goncalo Silva 26329
    @version 2.0
    @date 2017
 */
package edu.ufp.inf.lp2.projeto17;

import edu.princeton.cs.algs4.Bag;
import edu.princeton.cs.algs4.In;
import edu.princeton.cs.algs4.Stack;
import edu.princeton.cs.algs4.StdRandom;

/**
 * ****************************************************************************
 * Compilation: javac EdgeWeightedDigraph.java Execution: java
 * EdgeWeightedDigraph digraph.txt Dependencies: Bag.java DirectedEdge.java Data
 * files: http://algs4.cs.princeton.edu/44st/tinyEWD.txt
 * http://algs4.cs.princeton.edu/44st/mediumEWD.txt
 * http://algs4.cs.princeton.edu/44st/largeEWD.txt
 *
 * An edge-weighted digraph, implemented using adjacency lists.
 *
 *****************************************************************************
 */
/**
 * The {@code EdgeWeightedDigraph} class represents a 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 and self-loops are permitted.
 * <p>
 * This implementation uses an adjacency-lists representation, which is a
 * vertex-indexed array of {@link Bag} objects. All operations take constant
 * time (in the worst case) except iterating over the edges incident from a
 * given vertex, which takes time proportional to the number of such edges.
 * <p>
 * For additional documentation, see
 * <a href="http://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 EdgeWeightedDigraph {

    private static final String NEWLINE = System.getProperty("line.separator");

    private final int V;                // number of vertices in this digraph
    private int E;                      // number of edges in this digraph
    private Bag<DirectedEdge>[] adj;  //direçao          // adj[v] = adjacency list for vertex v
    private int[] indegree;             // indegree[v] = indegree of vertex v

    /**
     * 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 EdgeWeightedDigraph(int V) {
        if (V < 0) {
            throw new IllegalArgumentException("Number of vertices in a Digraph must be nonnegative");
        }
        this.V = V;
        this.E = 0;
        this.indegree = new int[V];
        adj = (Bag<DirectedEdge>[]) new Bag[V];
        for (int v = 0; v < V; v++) {
            adj[v] = new Bag<DirectedEdge>();
        }
    }

    /**
     * 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 EdgeWeightedDigraph(int V, int E) {
        this(V);
        if (E < 0) {
            throw new IllegalArgumentException("Number of edges in a Digraph must be nonnegative");
        }
        for (int i = 0; i < E; i++) {
            int v = StdRandom.uniform(V);
            int w = StdRandom.uniform(V);
            double weight = 0.01 * StdRandom.uniform(100);
            DirectedEdge e = new DirectedEdge(v, w, weight);
            addEdge(e);
        }
    }

    /**
     * Initializes an edge-weighted digraph from the specified input stream. The
     * format is the number of vertices <em>V</em>, followed by the number of
     * edges <em>E</em>, followed by <em>E</em> pairs of vertices and edge
     * weights, with each entry separated by whitespace.
     *
     * @param in the input stream
     * @throws IllegalArgumentException if the endpoints of any edge are not in
     * prescribed range
     * @throws IllegalArgumentException if the number of vertices or edges is
     * negative
     */
    public EdgeWeightedDigraph(In in) {
        this(in.readInt());
        int E = in.readInt();
        if (E < 0) {
            throw new IllegalArgumentException("Number of edges must be nonnegative");
        }
        for (int i = 0; i < E; i++) {
            int v = in.readInt();
            int w = in.readInt();
            validateVertex(v);
            validateVertex(w);
            double weight = in.readDouble();
            addEdge(new DirectedEdge(v, w, weight));
        }
    }

    /**
     * Initializes a new edge-weighted digraph that is a deep copy of {@code G}.
     *
     * @param G the edge-weighted digraph to copy
     */
    public EdgeWeightedDigraph(EdgeWeightedDigraph G) {
        this(G.V());
        this.E = G.E();
        for (int v = 0; v < G.V(); v++) {
            this.indegree[v] = G.indegree(v);
        }
        for (int v = 0; v < G.V(); v++) {
            // reverse so that adjacency list is in same order as original
            Stack<DirectedEdge> reverse = new Stack<DirectedEdge>();
            for (DirectedEdge e : G.adj[v]) {
                reverse.push(e);
            }
            for (DirectedEdge e : reverse) {
                adj[v].add(e);
            }
        }
    }

    /**
     * Returns the number of vertices in this edge-weighted digraph.
     *
     * @return the number of vertices in this edge-weighted digraph
     */
    public int V() {
        return V;
    }

    /**
     * Returns the number of edges in this edge-weighted digraph.
     *
     * @return the number of edges in this edge-weighted digraph
     */
    public int E() {
        return E;
    }

    // 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));
        }
    }

    /**
     * Adds the directed edge {@code e} to this edge-weighted digraph.
     *
     * @param e the edge
     * @throws IllegalArgumentException unless endpoints of edge are between
     * {@code 0} and {@code V-1}
     */
    public void addEdge(DirectedEdge e) {
        int v = e.from();
        int w = e.to();
        validateVertex(v);
        validateVertex(w);
        adj[v].add(e);
        indegree[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 adj[v];
    }

    /**
     * Returns the number of directed edges incident from vertex {@code v}. This
     * is known as the <em>outdegree</em> of vertex {@code v}.
     *
     * @param v the vertex
     * @return the outdegree of vertex {@code v}
     * @throws IllegalArgumentException unless {@code 0 <= v < V}
     */
    public int outdegree(int v) {
        validateVertex(v);
        return adj[v].size();
    }

    /**
     * Returns the number of directed edges incident to vertex {@code v}. This
     * is known as the <em>indegree</em> of vertex {@code v}.
     *
     * @param v the vertex
     * @return the indegree of vertex {@code v}
     * @throws IllegalArgumentException unless {@code 0 <= v < V}
     */
    public int indegree(int v) {
        validateVertex(v);
        return indegree[v];
    }

    /**
     * Returns all directed edges in this edge-weighted digraph. To iterate over
     * the edges in this edge-weighted digraph, use foreach notation:
     * {@code for (DirectedEdge e : G.edges())}.
     *
     * @return all edges in this edge-weighted digraph, as an iterable
     */
    public Iterable<DirectedEdge> edges() {
        Bag<DirectedEdge> list = new Bag<DirectedEdge>();
        for (int v = 0; v < V; v++) {
            for (DirectedEdge e : adj(v)) {
                list.add(e);
            }
        }
        return list;
    }

    /**
     * Returns a string representation of this edge-weighted digraph.
     *
     * @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();
    }

    /**
     * Unit tests the {@code EdgeWeightedDigraph} data type.
     *
     * @param args the command-line arguments
     */
    /*
    public static void main(String[] args) {
        In in = new In(args[0]);
        EdgeWeightedDigraph G = new EdgeWeightedDigraph(in);
        StdOut.println(G);
    }
     */
}