solved s08 ex4

08/src/main/java/ch/zhaw/ads/LabyrinthNode.java

@@ -1,6 +1,22 @@
 package ch.zhaw.ads;
 
-import java.util.*;
+class LabyrinthNode<E> extends Node<E> {
+    boolean mark;
+    LabyrinthNode<E> prev;
 
-public class LabyrinthNode<E> extends Node<E> {
+    public void setMark(boolean m) {
+        mark = m;
+    }
+
+    public boolean getMark() {
+        return mark;
+    }
+
+    public void setPrev(LabyrinthNode<E> prev) {
+        this.prev = prev;
+    }
+
+    public LabyrinthNode<E> getPrev() {
+        return prev;
+    }
 }

08/src/main/java/ch/zhaw/ads/LabyrinthServer.java

@@ -6,7 +6,7 @@ public class LabyrinthServer implements CommandExecutor {
     final double SCALE = 10;
 
     private ServerGraphics serverGraphics;
-    private Graph<LabyrinthNode, Edge> graph;
+    Graph<LabyrinthNode, Edge> graph;
 
     @Override
     public String execute(String command) {
@@ -17,19 +17,68 @@ public class LabyrinthServer implements CommandExecutor {
         serverGraphics.setColor(Color.BLACK);
         serverGraphics.fillRect(0, 0, 1, 1);
 
+        // read in data
         for (String record : command.split("\\r?\\n")) {
             String[] values = record.split(" ");
 
             try {
                 graph.addEdge(values[0], values[1], 0.0);
                 graph.addEdge(values[1], values[0], 0.0);
-            } catch (Throwable e) {}
+            } catch (Throwable e) {
+                e.printStackTrace();
+            }
 
             this.drawPath(serverGraphics, values[0], values[1], false);
         }
+
+
+        // find path
+        // start and goal are taken from the picture in the exercise
+        LabyrinthNode<Edge> start = graph.findNode("0-6");
+        LabyrinthNode<Edge> goal = graph.findNode("3-0");
+        this.unmarkAll();
+        if (this.search(start, goal)) {
+            LabyrinthNode<Edge> current = goal;
+            while (current.getPrev() != null) {
+                LabyrinthNode<Edge> prev = current.getPrev();
+                this.drawPath(serverGraphics, current.getName(), prev.getName(), true);
+                current = prev;
+            }
+        } else {
+            System.out.println("Failed to find path.");
+        }
+
         return serverGraphics.getTrace();
     }
 
+
+    private void unmarkAll() {
+        for (LabyrinthNode<Edge> node : graph.getNodes()) {
+            node.setMark(false);
+            node.setPrev(null);
+        }
+    }
+
+
+    private boolean search(LabyrinthNode<Edge> currentNode, LabyrinthNode<Edge> goal) {
+        currentNode.setMark(true);
+
+        if (currentNode.equals(goal)) return true;
+
+        for (Edge<LabyrinthNode> edge : currentNode.getEdges()) {
+            LabyrinthNode<Edge> sucessor = edge.getDest();
+            if (!sucessor.getMark()) {
+                if (this.search(sucessor, goal)) {
+                    sucessor.setPrev(currentNode);
+                    return true;
+                }
+            }
+        }
+        currentNode.setMark(false);
+        return false;
+    }
+
+
     private void drawPath(ServerGraphics g, String from, String to, boolean mouse) {
         if (mouse) serverGraphics.setColor(Color.RED);
         else serverGraphics.setColor(Color.WHITE);