Fixed Generation board to always generate a board that is solvable (fixed dfs null return).

src/Assignments/A1/Driver.java

@@ -25,18 +25,15 @@ public class Driver {
 
     public static void main(String[] args) {
         DFS solver = new DFS();
-//        Board board = new Board();
-//        Board result = solver.dfs(board, 0);
-//        System.out.println(result);
-//        Board board = BoardGenerator.generateBoard();
-//
-//        Board result = solver.dfs(board, 0, new ArrayList<String>());
-//        System.out.println(result);
-//
-        int[] temp = {0,8,3,5,1,6,4,7,2};
-        Board solvable = new Board(temp);
-        Board result = solver.dfs(solvable,0, new ArrayList<>());
-        System.out.println(result);
+        Board board = BoardGenerator.generateBoard();
+        Board result = solver.dfs(board, 0, new ArrayList<>());
+        int count = 0;
+        while (count != 100 || result != null) {
+            result = solver.dfs(board, 0, new ArrayList<>());
+            System.out.println(count);
+            count++;
+            board = BoardGenerator.generateBoard();
+        }
     }
 
 }

src/Assignments/A1/models/BoardGenerator.java

@@ -19,69 +19,14 @@ public class BoardGenerator {
      * @return a board that is solvable.
      */
     public static Board generateBoard() {
-
-        // Creates the initial board with default values.
-        Integer[] values = {1, 2, 3, 4, 5, 6, 7, 8};
-        List<Integer> random = new ArrayList<>(Arrays.asList(values));
-        Collections.shuffle(random);
-
-        Random gen = new Random();
-        int spaceLoc = gen.nextInt(9);
-        int[] pieces = new int[9];
-        for (int curr = 0; curr < values.length; curr++) {
-            pieces[curr] = random.get(curr);
-
+        Board ideal = new Board();
+        Random random = new Random();
+        int numOfMoves = random.nextInt(30,50);
+        for (int i = 0; i < numOfMoves; i++) {
+            List<Move> moves = ideal.getMoves();
+            Move randomMove = moves.get(random.nextInt(moves.size()));
+            ideal.swap(randomMove);
         }
-
-        // Checks if the board is solvable.
-        Board generated = new Board(pieces);
-        if (isSolvable(generated)) {
-            return generated;
-        } else { // If not it swaps the last two values (ignoring the space)
-            if (spaceLoc == 8) {
-                generated.swap(6,7);
-            } else if (spaceLoc == 7) {
-                generated.swap(6,8);
-            } else {
-                generated.swap(7,8);
-            }
-            generated = new Board(pieces);
-        }
-
-        // Puzzle is now solvable.
-        return generated;
+        return ideal;
     }
-
-    /**
-     * Checks if the board is solvable by checking the number of inversions.
-     * If the number of inversions is even, it is solvable, if not it is not solvable.
-     *
-     * @precondition board != null
-     * @postcondition none
-     *
-     * @param board the board being checked
-     * @return if the board has even inversion, True
-     *         if not,                          False
-     */
-    public static boolean isSolvable(Board board) {
-        if (board == null) {
-            return false;
-        }
-
-        // Holds the number of inversions
-        int inversions = 0;
-        int[] ordered = board.pieces;
-
-        // Counts the number of inversions
-        for (int index = 0; index < 9; index++) {
-            for (int invers = index+1; invers < 9; invers++) {
-                if (ordered[index] > ordered[invers]) {
-                    inversions++;
-                }
-            }
-        }
-        return (inversions % 2 == 0);
-    }
-
-
 }

src/Assignments/A1/resources/Parameters.java

@@ -9,6 +9,6 @@ package Assignments.A1.resources;
 public class Parameters {
 
     /* Used to prevent DFS from going down only 1 branch */
-    public static final int MAX_DEPTH = 31; // Max number of moves in 8-Puzzle's are 31 moves if solvable.
+    public static final int MAX_DEPTH = 100; // Max number of moves in 8-Puzzle's are 31 moves if solvable.
 
 }

src/Assignments/A1/solving_algorithms/DFS.java

@@ -17,7 +17,6 @@ public class DFS {
 
     public Board dfs(Board root, int depth, ArrayList<String> visited) {
         counter++;
-        System.out.println("Num of boards " + counter + " | Depth " + depth);
         if (root.equals(solved)) {
             return root;
         }