solved s07 ex04

07/src/main/java/ch/zhaw/ads/DijkstraNode.java

@@ -30,7 +30,6 @@ class DijkstraNode<E> extends Node<E> implements Comparable<DijkstraNode>  {
     }
 
     public int compareTo(DijkstraNode n) {
-        // TODO: implement
-        return 0;
+        return Double.compare(this.dist, n.getDist());
     }
 }

07/src/main/java/ch/zhaw/ads/RouteServer.java

@@ -1,17 +1,23 @@
 package ch.zhaw.ads;
 
 import java.util.Scanner;
+import java.util.Queue;
+import java.util.PriorityQueue;
 
 public class RouteServer implements CommandExecutor {
+    Graph<DijkstraNode, Edge> graph;
 
     @Override
     public String execute(String command) {
-        Graph<DijkstraNode, Edge> graph = this.readInput(command);
+        graph = this.readInput(command);
         StringBuffer result = new StringBuffer(100);
         for (Node node : graph.getNodes()) {
             result.append(node.getName() + "\n");
         }
         result.append("\"\n");
+
+
+        this.dijkstra("Winterthur", "Lugano");
         return result.toString();
     }
 
@@ -37,4 +43,42 @@ public class RouteServer implements CommandExecutor {
         scanner.close();
         return graph;
     }
+
+    private void dijkstra(String from, String to) {
+        Queue<DijkstraNode> pq = new PriorityQueue<DijkstraNode>();
+        DijkstraNode<Edge> start = graph.findNode(from);
+        DijkstraNode<Edge> goal = graph.findNode(to);
+        start.setDist(0);
+        pq.add(start);
+        while (!pq.isEmpty()) {
+            DijkstraNode<Edge> current = pq.poll();
+            current.setMark(true);
+            // implement equals for this
+            // if (current.equal(goal)) {
+            if (current.getName() == to) {
+                break;
+            }
+            for (Edge<DijkstraNode> edge : current.getEdges()) {
+                DijkstraNode<Edge> sucessor = edge.getDest();
+                if (!sucessor.getMark()) {
+                    double dist = edge.getWeight() + current.getDist();
+                    if (sucessor.getPrev() == null || dist < sucessor.getDist()) {
+                        sucessor.setDist(dist);
+                        sucessor.setPrev(current);
+                        pq.add(sucessor);
+                    }
+                }
+            }
+        }
+
+        System.out.println("\n\nShortest path:\n");
+        // print the shortest path
+        DijkstraNode<Edge> current = goal;
+        while (current.getPrev() != null) {
+            System.out.println(current.getName());
+            current = current.getPrev();
+        }
+        System.out.println(current.getName());
+        System.out.println("\n\n");
+    }
 }