Implemented A* at full state

src/search/EightPuzzleNode.java

@@ -17,6 +17,11 @@ public class EightPuzzleNode extends Node<int[][]>
         super(value, parent);
     }
 
+    private EightPuzzleNode(final int[][] value, final Node<int[][]> parent, final int heuristicCosts)
+    {
+        super(value, parent, heuristicCosts);
+    }
+
     @Override
     public boolean isTargetReached(final Node<int[][]> target)
     {
@@ -44,7 +49,8 @@ public class EightPuzzleNode extends Node<int[][]>
                     case LEFT -> new IntPair(x-1, y);
                 };
 
-                final var successor = this.swapStateField(newState, emptyPosition, posToSwap);
+                this.swapStateField(newState, emptyPosition, posToSwap);
+                final var successor = new EightPuzzleNode(newState, this, super.heuristicCosts+1);
 
                 if (!successor.valueEquals(this) && !successor.valueEquals(super.getParent()))
                 {
@@ -121,35 +127,11 @@ public class EightPuzzleNode extends Node<int[][]>
         return copy;
     }
 
-    private EightPuzzleNode swapStateField(final int[][] newState, final IntPair emptyPos, final IntPair posToSwap)
+    private void swapStateField(final int[][] newState, final IntPair emptyPos, final IntPair posToSwap)
     {
         final var tmp = newState[posToSwap.getY()][posToSwap.getX()];
         newState[posToSwap.getY()][posToSwap.getX()] = newState[emptyPos.getY()][emptyPos.getX()];
         newState[emptyPos.getY()][emptyPos.getX()] = tmp;
-
-        return new EightPuzzleNode(newState, this);
-    }
-
-    private class IntPair
-    {
-        private final int x;
-        private final int y;
-
-        public IntPair(final int x, final int y)
-        {
-            this.x = x;
-            this.y = y;
-        }
-
-        public int getX()
-        {
-            return x;
-        }
-        public int getY()
-        {
-            return y;
-        }
-
     }
 
     private enum Direction

src/search/IntPair.java

@@ -0,0 +1,23 @@
+package search;
+
+public class IntPair
+{
+    private final int x;
+    private final int y;
+
+    public IntPair(final int x, final int y)
+    {
+        this.x = x;
+        this.y = y;
+    }
+
+    public int getX()
+    {
+        return x;
+    }
+    public int getY()
+    {
+        return y;
+    }
+
+}

src/search/Node.java

@@ -1,24 +1,30 @@
 package search;
 
-import search.heuristic.Heuristic;
-
 import java.util.List;
 import java.util.Objects;
 
 public abstract class Node<T>
 {
     protected final T value;
+    protected int heuristicCosts;
     private final Node<T> parent;
+    private int heuristicEstimation;
 
     protected Node(final T value)
     {
-        this(value, null);
+        this(value, null, 0);
     }
 
     protected Node(final T value, final Node<T> parent)
+    {
+        this(value, parent, 0);
+    }
+
+    protected Node(final T value, final Node<T> parent, final int heuristicCosts)
     {
         this.value = Objects.requireNonNull(value);
         this.parent = parent;
+        this.heuristicCosts = heuristicCosts;
     }
 
     public T getValue()
@@ -31,6 +37,16 @@ public abstract class Node<T>
         return this.parent;
     }
 
+    public int getHeuristic()
+    {
+        return heuristicCosts + heuristicEstimation;
+    }
+
+    public void setHeuristicEstimation(final int heuristicEstimation)
+    {
+        this.heuristicEstimation = heuristicEstimation;
+    }
+
     public abstract boolean isTargetReached(final Node<T> target);
     public abstract List<Node<T>> generateSuccessors();
 }

src/search/heuristic/AStar.java

@@ -7,16 +7,17 @@ import java.util.PriorityQueue;
 
 public class AStar<T>
 {
-    private final Heuristic<T> heuristicFunction;
+    private final HeuristicEstimationFunction<T> heuristicFunction;
 
-    public AStar(final Heuristic<T> heuristicFunction)
+    public AStar(final HeuristicEstimationFunction<T> heuristicFunction)
     {
         this.heuristicFunction = heuristicFunction;
     }
 
     public Node<T> heuristicSearch(final Node<T> start, final Node<T> target)
     {
-        final var nodes = new PriorityQueue<Node<T>>(Comparator.comparingInt(node -> heuristicFunction.heuristic(node, target)));
+        final var nodes = new PriorityQueue<Node<T>>(Comparator.comparingInt(Node::getHeuristic));
+        start.setHeuristicEstimation(this.heuristicFunction.heuristicEstimation(start, target));
         nodes.add(start);
 
         while (true)
@@ -33,7 +34,14 @@ public class AStar<T>
                 return node;
             }
 
-            nodes.addAll(node.generateSuccessors());
+            final var successors = node.generateSuccessors();
+
+            for (final var successor : successors)
+            {
+                successor.setHeuristicEstimation(this.heuristicFunction.heuristicEstimation(successor, target));
+            }
+
+            nodes.addAll(successors);
         }
     }
 }

src/search/heuristic/Heuristic.java

@@ -1,8 +0,0 @@
-package search.heuristic;
-
-import search.Node;
-
-public interface Heuristic<T>
-{
-    int heuristic(Node<T> node, Node<T> target);
-}

src/search/heuristic/HeuristicEstimationFunction.java

@@ -0,0 +1,8 @@
+package search.heuristic;
+
+import search.Node;
+
+public interface HeuristicEstimationFunction<T>
+{
+    int heuristicEstimation(Node<T> node, Node<T> target);
+}

test/search/heuristic/AStarTest.java

@@ -2,20 +2,20 @@ package search.heuristic;
 
 import org.junit.jupiter.api.Test;
 import search.EightPuzzleNode;
+import search.IntPair;
 import search.Node;
 
-import static org.junit.jupiter.api.Assertions.*;
 import static search.SearchTestUtils.printSolution;
 
 class AStarTest
 {
     @Test
-    void shouldReturnCorrectTargetCubekNodeHeuristik1()
+    void shouldReturnCorrectTargetCubekNodeHeuristic1()
     {
         final int[][] state = {
-                {3, 5, 0},
+                {2, 0, 4},
-                {1, 2, 6},
+                {6, 7, 1},
-                {4, 7, 8}
+                {8, 5, 3}
         };
         final var root = new EightPuzzleNode(state);
 
@@ -63,7 +63,7 @@ class AStarTest
         {
             for (var col = 0; col < value[row].length; col++)
             {
-                if (value[row][col] != targetValue[row][col])
+                if (value[row][col] != 0 && value[row][col] != targetValue[row][col])
                 {
                     counter++;
                 }
@@ -75,6 +75,40 @@ class AStarTest
 
     private int h2(final Node<int[][]> node, final Node<int[][]> target)
     {
-        return 0;
+        final var value = node.getValue();
+        final var targetValue = target.getValue();
+        var manhattanDistance = 0;
+
+        for (int i = 1; i <= 8; i++)
+        {
+            final var targetPos = detectPositionOf(i, targetValue);
+            final var actualPos = detectPositionOf(i, value);
+
+            if (targetPos != null && actualPos != null)
+            {
+                final var xDistance = Math.abs(targetPos.getX() - actualPos.getX());
+                final var yDistance = Math.abs(targetPos.getY() - actualPos.getY());
+
+                manhattanDistance += xDistance + yDistance;
+            }
+        }
+
+        return manhattanDistance;
+    }
+
+    private IntPair detectPositionOf(final int i, final int[][] value)
+    {
+        for (var row = 0; row < value.length; row++)
+        {
+            for (var col = 0; col < value[row].length; col++)
+            {
+                if (value[row][col] == i)
+                {
+                    return new IntPair(col, row);
+                }
+            }
+        }
+
+        return null;
     }
 }