Added functionality to allow for a board to be generated and check if the board is solvable.

src/Assignments/A1/Driver.java

@@ -3,6 +3,10 @@ package Assignments.A1;
 // Potentially will be changed to an UI Implementation with JavaFX if time permits.
 
 
+import Assignments.A1.managers.BoardGenerator;
+import Assignments.A1.models.Board;
+import Assignments.A1.models.Piece;
+
 /**
  * Board will be used to save locations in a 2D array.
  *
@@ -16,6 +20,24 @@ package Assignments.A1;
  */
 public class Driver {
 
+    public static void main(String[] args) {
+        Board board = BoardGenerator.generateBoard();
+        System.out.println(board);
+        System.out.println(BoardGenerator.isSolvable(board));
 
+        Piece[] pieces = new Piece[9];
+        pieces[0] = new Piece(0,7);
+        pieces[1] = null;
+        pieces[2] = new Piece(2,5);
+        pieces[3] = new Piece(3,1);
+        pieces[4] = new Piece(4,2);
+        pieces[5] = new Piece(5,4);
+        pieces[6] = new Piece(6,6);
+        pieces[7] = new Piece(7,3);
+        pieces[8] = new Piece(8,8);
+
+        board = new Board(pieces);
+        System.out.println(BoardGenerator.isSolvable(board));
+    }
 
 }

src/Assignments/A1/managers/BoardGenerator.java

@@ -1,5 +1,95 @@
 package Assignments.A1.managers;
 
+import Assignments.A1.models.Board;
+import Assignments.A1.models.Piece;
+
+import java.util.*;
+
+/**
+ * This class is used to create and check boards.
+ *
+ * @author Jonathan Turner
+ * @version Spring 2024
+ */
 public class BoardGenerator {
 
+    /**
+     * Generates a random 8-Puzzle that is always solvable.
+     *
+     * @precondition none
+     * @postcondition none
+     *
+     * @return a board that is solvable.
+     */
+    public static Board generateBoard() {
+
+        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);
+        Piece[] pieces = new Piece[9];
+        for (int curr = 0; curr < values.length; curr++) {
+            if (curr < spaceLoc) {
+                pieces[curr] = new Piece(curr,random.get(curr));
+            } else {
+                pieces[curr+1] = new Piece(curr+1,random.get(curr));
+            }
+        }
+
+        // Checks if the board is solveable.
+        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) {
+                pieces[7].setLocation(6);
+                pieces[6].setLocation(7);
+            } else if (spaceLoc == 7) {
+                pieces[8].setLocation(6);
+                pieces[6].setLocation(8);
+            } else {
+                pieces[7].setLocation(6);
+                pieces[6].setLocation(7);
+            }
+            generated = new Board(pieces);
+        }
+
+        // Puzzle is now solvable.
+        return generated;
+    }
+
+    /**
+     * 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;
+        Piece[] ordered = board.getPiecesInOrder();
+
+        // Counts the number of inversions
+        for (int index = 0; index < 8; index++) {
+            for (int invers = index+1; invers < 8; invers++) {
+                if (ordered[index].getValue() > ordered[invers].getValue()) {
+                    inversions++;
+                }
+            }
+        }
+        return (inversions % 2 == 0);
+    }
+
+
 }

src/Assignments/A1/models/Board.java

@@ -1,6 +1,7 @@
 package Assignments.A1.models;
 
 import java.util.Arrays;
+import java.util.Random;
 
 /**
  * This class keeps track of the current state (whether in permutation or not) of the board.
@@ -45,6 +46,21 @@ public class Board {
         }
     }
 
+    /**
+     * Constructor used to create a board with a pre-provided piece list.
+     *
+     * @precondition pieces == 9
+     * @postcondition a board is created with given locations
+     *
+     * @param pieces the provided state.
+     */
+    public Board(Piece[] pieces) {
+        if (pieces.length != 9) {
+            throw new IllegalArgumentException("The pieces list must be size 9.");
+        }
+        this.pieces = pieces;
+    }
+
 
     /**
      * Checks the status of a place on the board. If the location is taken or not.
@@ -195,10 +211,10 @@ public class Board {
         if (this.getClass() != o.getClass()) {
             return false;
         }
-        Board other = (Board) o;
+        Piece[] other = ((Board) o).getPiecesInOrder();
-        for (int i = 0; i < 9; i++) {
+        Piece[] ordered = this.getPiecesInOrder();
-            if (this.pieces[i].getValue() != other.pieces[i].getValue()
+        for (int curr = 0; curr < ordered.length; curr++) {
-                || this.pieces[i].getLoc() != other.pieces[i].getLoc()) {
+            if (ordered[curr] != other[curr]) {
                 return false;
             }
         }
@@ -213,7 +229,11 @@ public class Board {
     public String toString() {
         String result = "";
         for (int i = 0; i < 9; i++) {
-            result += i + " ";
+            if (pieces[i] == null) {
+                result += 0 + " ";
+            } else {
+                result += pieces[i] + " ";
+            }
             if ((i+1) % 3 == 0) {
                 result += "\n";
             }

src/Assignments/A1/models/EightPuzzle.java

@@ -1,11 +1,16 @@
 package Assignments.A1.models;
 
+import java.util.ArrayList;
+import java.util.List;
+
 /**
  * @author Jonathan Turner
  * @version Spring 2024
  */
 public class EightPuzzle {
 
+    private List<Board> boards = new ArrayList<>();
+
 
 
 }

src/Assignments/A1/models/Piece.java

@@ -60,6 +60,21 @@ public class Piece {
         this.setLoc(newLoc);
     }
 
+    /**
+     * Should only be used when creating the board to set its location.
+     *
+     * @precondition location is valid
+     * @postcondition new location set
+     *
+     * @param newLoc the new location
+     */
+    public void setLocation(int newLoc) {
+        if (invalidLocation(newLoc)) {
+            throw new IllegalArgumentException("The location should be valid.");
+        }
+        this.loc = newLoc;
+    }
+
     /**
      * Gets the location of the piece.
      *
@@ -110,6 +125,17 @@ public class Piece {
         return board.isTaken(desiredLoc);
     }
 
+    /**
+     * Turns any string call of the class to just its value.
+     * @precondition none
+     * @postcondition none
+     * @return the value of the piece.
+     */
+    @Override
+    public String toString() {
+        return String.valueOf(this.value);
+    }
+
     /* Private Methods Below. End of Java Docs. */
 
     /* Sets the location for both Moving and Initialization. */