WeightedGraph.java

public class WeightedGraph {

   private int [][]  edges;  // adjacency matrix
   private Object [] labels;

   public WeightedGraph (int n) {
      edges  = new int [n][n];
      labels = new Object[n];
   }


   public int size() { return labels.length; }

   public void   setLabel (int vertex, Object label) { labels[vertex]=label; }
   public Object getLabel (int vertex)               { return labels[vertex]; }

   public void    addEdge    (int source, int target, int w)  { edges[source][target] = w; }
   public boolean isEdge     (int source, int target)  { return edges[source][target]>0; }
   public void    removeEdge (int source, int target)  { edges[source][target] = 0; }
   public int     getWeight  (int source, int target)  { return edges[source][target]; }

   public int [] neighbors (int vertex) {
      int count = 0;
      for (int i=0; i<edges[vertex].length; i++) {
	 if (edges[vertex][i]>0) count++;
      }
      final int[]answer= new int[count];
      count = 0;
      for (int i=0; i<edges[vertex].length; i++) {
	 if (edges[vertex][i]>0) answer[count++]=i;
      }
      return answer;
   }

   public void print () {
      for (int j=0; j<edges.length; j++) {
	 System.out.print (labels[j]+": ");
	 for (int i=0; i<edges[j].length; i++) {
	    if (edges[j][i]>0) System.out.print (labels[i]+":"+edges[j][i]+" ");
	 }
	 System.out.println ();
      }
   }

   public static void main (String args[]) {
      final WeightedGraph t = new WeightedGraph (6);
      t.setLabel (0, "v0");
      t.setLabel (1, "v1");
      t.setLabel (2, "v2");
      t.setLabel (3, "v3");
      t.setLabel (4, "v4");
      t.setLabel (5, "v5");
      t.addEdge (0,1,2);
      t.addEdge (0,5,9);
      t.addEdge (1,2,8);
      t.addEdge (1,3,15);
      t.addEdge (1,5,6);
      t.addEdge (2,3,1);
      t.addEdge (4,3,3);
      t.addEdge (4,2,7);
      t.addEdge (5,4,3);
      t.print();

      final int [] pred = Dijkstra.dijkstra (t, 0);
      for (int n=0; n<6; n++) {
	 Dijkstra.printPath (t, pred, 0, n);
      }
   }

}