Finished tests

src/search/breadthfirstsearch/EightPuzzleNode.java

@@ -3,13 +3,15 @@ package search.breadthfirstsearch;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
+import java.util.Objects;
 import java.util.stream.IntStream;
 
 public class EightPuzzleNode implements Node
 {
     private int[][] state;
 
-    public EightPuzzleNode(int[][] state) {
+    public EightPuzzleNode(int[][] state)
+    {
         if (!isValidState(state))
         {
             throw new IllegalArgumentException("Allowed numbers are only 0-8 and they must exist uniquely.");
@@ -19,44 +21,137 @@ public class EightPuzzleNode implements Node
     }
 
     @Override
-    public boolean isTargetReached(Node target) {
+    public boolean isTargetReached(Node target)
+    {
         return Arrays.equals(this.state, ((EightPuzzleNode) target).state);
     }
 
     @Override
-    public List<Node> generateSuccessors() {
+    public List<Node> generateSuccessors()
-        ArrayList<Node> successors = new ArrayList<>();
+    {
+        var successors = new ArrayList<Node>();
+        var emptyPosition = Objects.requireNonNull(detectEmptyPosition());
+        int x = emptyPosition.getRight();
+        int y = emptyPosition.getLeft();
 
-        successors.add(new EightPuzzleNode(null));
+        for (Direction dir : Direction.values())
+        {
+            var newState = copyOfState();
+
+            try
+            {
+                int tmp;
+                switch (dir)
+                {
+                    case TOP:
+                        tmp = newState[y-1][x];
+                        newState[y-1][x] = newState[y][x];
+                        newState[y][x] = tmp;
+                        successors.add(new EightPuzzleNode(newState));
+                        break;
+                    case RIGHT:
+                        tmp = newState[y][x+1];
+                        newState[y][x+1] = newState[y][x];
+                        newState[y][x] = tmp;
+                        successors.add(new EightPuzzleNode(newState));
+                        break;
+                    case DOWN:
+                        tmp = newState[y+1][x];
+                        newState[y+1][x] = newState[y][x];
+                        newState[y][x] = tmp;
+                        successors.add(new EightPuzzleNode(newState));
+                        break;
+                    case LEFT:
+                        tmp = newState[y][x-1];
+                        newState[y][x-1] = newState[y][x];
+                        newState[y][x] = tmp;
+                        successors.add(new EightPuzzleNode(newState));
+                        break;
+                }
+            }
+            catch (ArrayIndexOutOfBoundsException ignored)
+            {
+            }
+        }
 
         return successors;
     }
 
+    public int[][] getState()
+    {
+        return state;
+    }
+
     private boolean isValidState(int[][] state)
     {
-        int[] numbers = Arrays.stream(state).flatMapToInt(IntStream::of).toArray();
+        var numbers = Arrays.stream(state).flatMapToInt(IntStream::of).toArray();
-        int[] countOfNumbers = new int[9];
 
-        for (int i : numbers)
+        return numbersAreInAllowedRange(numbers) && numbersAreUnique(numbers);
-        {
-            try
-            {
-                countOfNumbers[i]++;
     }
-            catch (ArrayIndexOutOfBoundsException e)
+
+    private boolean numbersAreInAllowedRange(int[] numbers)
     {
-                return false;
+        return Arrays.stream(numbers).min().getAsInt() == 0 && Arrays.stream(numbers).max().getAsInt() == 8;
+    }
+
+    private boolean numbersAreUnique(int[] numbers)
+    {
+        return Arrays.stream(numbers).count() == Arrays.stream(numbers).distinct().count();
+    }
+
+    private IntPair detectEmptyPosition()
+    {
+        for (int row = 0; row < this.state.length; row++)
+        {
+            for (int col = 0; col < this.state[row].length; col++)
+            {
+                if (state[row][col] == 0)
+                {
+                    return new IntPair(row, col);
+                }
             }
         }
 
-        for (int i : countOfNumbers)
+        return null;
-        {
-            if (i == 0 || i > 1)
-            {
-                return false;
-            }
     }
 
-        return true;
+    private int[][] copyOfState()
+    {
+        var copy = new int[3][3];
+
+        for (int y = 0; y < copy.length; y++)
+        {
+            System.arraycopy(this.state[y], 0, copy[y], 0, copy.length);
+        }
+
+        return copy;
+    }
+
+    private class IntPair
+    {
+        private final int left;
+
+        private final int right;
+
+        public IntPair(int left, int right)
+        {
+            this.left = left;
+            this.right = right;
+        }
+
+        public int getLeft()
+        {
+            return left;
+        }
+        public int getRight()
+        {
+            return right;
+        }
+
+    }
+    private enum Direction
+    {
+        TOP, RIGHT, DOWN, LEFT
+
     }
 }

test/search/breadthfirstsearch/BreadthFirstSearchTest.java

@@ -0,0 +1,14 @@
+package search.breadthfirstsearch;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class BreadthFirstSearchTest
+{
+    @Test
+    void shouldReturnCorrectTarget()
+    {
+
+    }
+}

test/search/breadthfirstsearch/EightPuzzleNodeTest.java

@@ -3,10 +3,9 @@ package search.breadthfirstsearch;
 import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.Test;
 
+import java.util.Arrays;
 import java.util.List;
 
-import static org.junit.jupiter.api.Assertions.*;
-
 class EightPuzzleNodeTest
 {
     @Test
@@ -84,4 +83,45 @@ class EightPuzzleNodeTest
         Assertions.assertFalse(successors.isEmpty());
     }
 
+    @Test
+    public void shouldReturnEmptyListOfSuccessors()
+    {
+    }
+
+    @Test
+    public void shouldReturnCorrectSuccessors()
+    {
+        int[][] state = {
+                {7, 1, 6},
+                {0, 4, 2},
+                {3, 5, 8}
+        };
+
+        var node = new EightPuzzleNode(state);
+        var successors = node.generateSuccessors();
+
+        Assertions.assertEquals(3, successors.size());
+
+        int[][] newState1 = {
+                {0, 1, 6},
+                {7, 4, 2},
+                {3, 5, 8}
+        };
+
+        int[][] newState2 = {
+                {7, 1, 6},
+                {4, 0, 2},
+                {3, 5, 8}
+        };
+
+        int[][] newState3 = {
+                {7, 1, 6},
+                {3, 4, 2},
+                {0, 5, 8}
+        };
+
+        Assertions.assertArrayEquals(newState1, ((EightPuzzleNode) successors.get(0)).getState());
+        Assertions.assertArrayEquals(newState2, ((EightPuzzleNode) successors.get(1)).getState());
+        Assertions.assertArrayEquals(newState3, ((EightPuzzleNode) successors.get(2)).getState());
+    }
 }