001
002
003
004
005
006
007
008
009
010
011
012
013
014
015
016
017
018
019
020
021
022
023
024
025
026
027
028
029
030
031
032
033
034
035
036
037
038
039
040
041
042
043
044
045
046
047
048
049
050
051
052
053
054
055
056
057
058
059
060
061
062
063
064
065
066
067
068
069
070
071
072
073
074
075
076
077
078
079
080
081
082
083
084
085
086
087
088
089
090
091
092
093
094
095
096
097
098
099
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
// Exercise 4.4.2 (Solution published at http://algs4.cs.princeton.edu/)
package algs44;
import stdlib.*;
import algs13.Bag;
import algs13.Stack;
/**
 *  The <tt>EdgeWeightedDigraph</tt> class represents an directed graph of vertices
 *  named 0 through V-1, where each edge has a real-valued weight.
 *  It supports the following operations: add an edge to the graph,
 *  iterate over all of edges leaving a vertex.
 *  Parallel edges and self-loops are permitted.
 *  <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.
 */

public class EdgeWeightedDigraph {
  private final int V;
  private int E;
  private final Bag<DirectedEdge>[] adj;

  /**
   * Create an empty edge-weighted digraph with V vertices.
   */
  @SuppressWarnings("unchecked")
  public EdgeWeightedDigraph(int V) {
    if (V < 0) throw new Error("Number of vertices must be nonnegative");
    this.V = V;
    this.E = 0;
    adj = new Bag[V];
    for (int v = 0; v < V; v++)
      adj[v] = new Bag<>();
  }

  /**
   * Create a random edge-weighted graph with V vertices and E edges with no parallel edges or self loops.
   * The expected running time is proportional to V + E.
   */
  public EdgeWeightedDigraph(int V, int E) { this (V, E, false); }
  /**
   * Create a random edge-weighted graph with V vertices and E edges.
   * The expected running time is proportional to V + E.
   */
  public EdgeWeightedDigraph(int V, int E, boolean allowParallelEdgesAndSelfLoops) {
    this(V);
    if (E < 0) throw new Error("Number of edges must be nonnegative");
    if (allowParallelEdgesAndSelfLoops) {
      for (int i = 0; i < E; i++) {
        int v = (int) (Math.random() * V);
        int w = (int) (Math.random() * V);
        double weight = Math.round(100 * Math.random()) / 100.0;
        DirectedEdge e = new DirectedEdge(v, w, weight);
        addEdge(e);
      }
    } else {
      if (E > V*(V-1)/2) throw new Error("Number of edges must be less than V*(V-1)/2");
      newEdge: while (E>0) {
        int v = (int) (Math.random() * V);
        int w = (int) (Math.random() * V);
        if (v == w) continue;
        for (DirectedEdge e: adj[v])
          if (w == e.to())
            continue newEdge;
        double weight = Math.round(100 * Math.random()) / 100.0;
        DirectedEdge e = new DirectedEdge(v, w, weight);
        addEdge(e);
        E--;
      }
    }
  }
  /**
   * Create an edge-weighted digraph from input stream.
   */
  public EdgeWeightedDigraph(In in) {
    this(in.readInt());
    int E = in.readInt();
    for (int i = 0; i < E; i++) {
      int v = in.readInt();
      int w = in.readInt();
      double weight = in.readDouble();
      addEdge(new DirectedEdge(v, w, weight));
    }
  }

  /**
   * Copy constructor.
   */
  public EdgeWeightedDigraph(EdgeWeightedDigraph G) {
    this(G.V());
    this.E = G.E();
    for (int v = 0; v < G.V(); v++) {
      // reverse so that adjacency list is in same order as original
      Stack<DirectedEdge> reverse = new Stack<>();
      for (DirectedEdge e : G.adj[v]) {
        reverse.push(e);
      }
      for (DirectedEdge e : reverse) {
        adj[v].add(e);
      }
    }
  }

  /**
   * Return the number of vertices in this digraph.
   */
  public int V() {
    return V;
  }

  /**
   * Return the number of edges in this digraph.
   */
  public int E() {
    return E;
  }


  /**
   * Add the edge e to this digraph.
   */
  public void addEdge(DirectedEdge e) {
    int v = e.from();
    adj[v].add(e);
    E++;
  }


  /**
   * Return the edges leaving vertex v as an Iterable.
   * To iterate over the edges leaving vertex v, use foreach notation:
   * <tt>for (DirectedEdge e : graph.adj(v))</tt>.
   */
  public Iterable<DirectedEdge> adj(int v) {
    return adj[v];
  }

  /**
   * Return all edges in this graph as an Iterable.
   * To iterate over the edges, use foreach notation:
   * <tt>for (DirectedEdge e : graph.edges())</tt>.
   */
  public Iterable<DirectedEdge> edges() {
    Bag<DirectedEdge> list = new Bag<>();
    for (int v = 0; v < V; v++) {
      for (DirectedEdge e : adj(v)) {
        list.add(e);
      }
    }
    return list;
  }

  /**
   * Return number of edges leaving v.
   */
  public int outdegree(int v) {
    return adj[v].size();
  }



  /**
   * Return a string representation of this graph.
   */
  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();
  }

  /**
   * Save a graphviz representation of the graph.
   * See <a href="http://www.graphviz.org/">graphviz.org</a>.
   */
  public void toGraphviz(String filename) {
    GraphvizBuilder gb = new GraphvizBuilder ();
    for (int v = 0; v < V; v++) {
      gb.addNode (v);
      for (DirectedEdge e : adj[v]) {
        int w = e.to();
        gb.addLabeledEdge (v, w, e.weight ());
      }
    }
    gb.toFile (filename);
  }

  /**
   * Test client.
   */
  public static void main(String[] args) {
    //args = new String [] { "data/tinyEWDAG.txt" };
    //args = new String [] { "data/tinyEWD.txt" };
    //args = new String [] { "data/tinyEWDn.txt" };
    //args = new String [] { "data/tinyEWDnc.txt" };
    args = new String [] { "20", "20" };

    EdgeWeightedDigraph G;
    if (args.length == 1) {
      In in = new In(args[0]);
      G = new EdgeWeightedDigraph(in);
    } else {
      int V = Integer.parseInt (args[0]);
      int E = Integer.parseInt (args[1]);
      G = new EdgeWeightedDigraph(V, E, false);
    }
    StdOut.println(G);
    G.toGraphviz ("g.png");
  }

}