hw1p1, Java - rextester

hw1p1

import java.util.Random;

class Board {
	public int[][] pieces;
	public int value;
	public int blankRow;
	public int blankCol;
    public int lastMove;
    public int numMoves;
	
	public Board() {
		pieces = new int[3][3];
        numMoves = 0;
	}
	
	public Board(Board b) {
		pieces = new int[3][3];
		for (int i=0; i<3; i++) {
			for (int k=0; k<3; k++) {
				pieces[i][k] = b.pieces[i][k];
			}
		}
		
		value = b.value;
		blankRow = b.blankRow;
		blankCol = b.blankCol;
        lastMove = b.lastMove;
        numMoves = b.numMoves;
	}
	
	public void printState() {
		
		for (int i=0; i<3; i++) {
			for (int k=0; k<3; k++) {
				System.out.print(pieces[i][k]+" ");
			}
			System.out.println();
		}
		System.out.println("---- Value: "+evaluateBoard()+" ----");
	}
	
	public int moveBlankUp() {
		if (blankRow == 0) return -1;
		pieces[blankRow][blankCol] = pieces[blankRow-1][blankCol];
		pieces[blankRow-1][blankCol] = 0;
		
		blankRow -= 1;
		evaluateBoard();
        lastMove = 0;
        numMoves++;
		
		return 0;
	}
	
	public int moveBlankDown() {
		if (blankRow == 2) return -1;
		pieces[blankRow][blankCol] = pieces[blankRow+1][blankCol];
		pieces[blankRow+1][blankCol] = 0;
		
		blankRow += 1;
		evaluateBoard();
        lastMove = 1;
        numMoves++;
		
		return 0;
	}
	
	public int moveBlankLeft() {
		if (blankCol == 0) return -1;
		pieces[blankRow][blankCol] = pieces[blankRow][blankCol-1];
		pieces[blankRow][blankCol-1] = 0;
		
		blankCol -= 1;
		evaluateBoard();
        lastMove = 2;
        numMoves++;
		
		return 0;
	}
	
	public int moveBlankRight() {
		if (blankCol == 2) return -1;
		pieces[blankRow][blankCol] = pieces[blankRow][blankCol+1];
		pieces[blankRow][blankCol+1] = 0;
		
		blankCol += 1;
		evaluateBoard();
        lastMove = 3;
        numMoves++;
		
		return 0;
	}
	
	public int evaluateBoard() {
		int score = 0;
		
		for (int i=0; i<3; i++) {
			for (int k=0; k<3; k++) {
				score += distanceFromOrigin(pieces[i][k], i, k);
			}
		}
		
		value = score;
		return score;
	}
	
	public int distanceFromOrigin(int piece, int row, int col) {
		int originRow = (int)Math.floor(piece/3);
		int originCol = piece % 3;
		
		return Math.abs(row-originRow) + Math.abs(col-originCol);
	}
	
	
}

class BoardNode {
	public Board board;
	public Board[] children;
	
	public BoardNode(Board b) {
		board = new Board(b);
		children = new Board[4];
	}
	
	public void createChildren() {
		children = new Board[4];
	
		for (int i=0; i<4; i++) {
			Board b = new Board(board);
			
			int result = 0;
			
			if (i == 0) result = b.moveBlankUp();
			if (i == 1) result = b.moveBlankDown();
			if (i == 2) result = b.moveBlankLeft();
			if (i == 3) result = b.moveBlankRight();
			
			if (result == 0) {
				b.evaluateBoard();
				children[i] = b;
			}
			else children[i] = null;
		}
		
	}
	
	public void printChildren() {
		for (int i=0; i<children.length; i++) {
			if (children[i] != null) {
				children[i].printState();
			}
		}
	}
	
	public int getBestMove() {
		int minIndex = 0;
		int minScore = 100000;
		
		for (int i=0; i<children.length; i++) {
			if (children[i] != null) {
				if (children[i].value < minScore) {
					minScore = children[i].value;
					minIndex = i;
				}
			}
		}
	
		return minIndex;
	}
	
	public void solvePuzzle() {
		while (board.value != 0 ) {
			createChildren();
			int move = getBestMove();
			if (move == 0 && board.lastMove != 1) board.moveBlankUp();
			else if (move == 1 && board.lastMove != 0) board.moveBlankDown();
			else if (move == 2 && board.lastMove != 3) board.moveBlankLeft();
			else if (move == 3 && board.lastMove != 2) board.moveBlankRight();
            else {
                Random randomGenerator = new Random();
                int rMove = randomGenerator.nextInt(4);
                
                if (rMove == 0) board.moveBlankUp();
                if (rMove == 1) board.moveBlankDown();
                if (rMove == 2) board.moveBlankLeft();
                if (rMove == 3) board.moveBlankRight();
            }
			//board.printState();
			//System.out.println("#####");
			//printChildren();
		}
	}
	
}
	
    
class Rextester {
    public static void getPiecePosition(int value) {
        //if (value < 0 || value > 8) return -1;
        
        int row = (int)Math.floor(value/3);
        int col = value % 3;
        
        System.out.println(value+": ("+row+", "+col+")");
    }

public static void main(String args[]) {
		Board b = new Board();
        
        String s = "1,0,2,3,4,5,6,7,8";
        String[] vals = s.split(",");
        
        for (int i=0; i<vals.length; i++) {
            int row = (int)Math.floor(i/3);
            int col = i % 3;
            b.pieces[row][col] = Integer.parseInt(vals[i]);
            
            if (vals[i].equals("0")) {
                b.blankRow = row;
                b.blankCol = col;
            }
        }
				
		BoardNode bNode = new BoardNode(b);
        bNode.board.printState();
        bNode.solvePuzzle();
		bNode.board.printState();
        System.out.println("\nNumber of moves taken: "+bNode.board.numMoves);
    }
}


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If by any chance you are reading this: What does this program do exactly? I am really confused. And there's no comments either.

by James Collins, 4 months ago

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