Discussion on Simplified Chess Engine Challenge

4 years ago+ 0 comments

Some fun debugging output for people sticking with the original data structure -- will show what the whole chess board looks like with nice chess unicode characters:

turn : 1

 4 ♞⬛♜⬛
 3 ⬛♛♘♖
 2 ⬜⬛♜⬛
 1 ⬛♝⬛♕
    A B C D

turn : 2

 4 ♞⬛♜⬛
 3 ⬛♛♘♖
 2 ♝⬛♜⬛
 1 ⬛⬜⬛♕
    A B C D

Code:

    // displays the full board for debugging
    static void debugBoard(char[][] white, char[][] black){
        String padding = " "; //changing this helps with weird output
        char[] board = new char[16];
        char[][][] players = new char[2][][];
        if(white == null || black == null)
            return;
        players[0] = black; players[1] = white;
        for(int i = 0; i < board.length; i++)
            board[i] = (i%2==(((i/4)%2==1)?1:0))?(char)11036:(char)11035; // unicode for white and black squares
        for(int i = 0; i < players.length; i++){
            for(char[] piece: players[i]){
                if(piece == null || piece.length < 3)
                    continue;
                int x = (piece[1] - '0')-17; // A becomes 1, B becomes 2 etc
                int y = (piece[2] - '0'); // same thing but with numbers
                int pieceUnicode = 0;
                switch(piece[0]){
                    case 'Q': pieceUnicode = 9813; break;
                    case 'R': pieceUnicode = 9814; break;
                    case 'B': pieceUnicode = 9815; break;
                    case 'N': pieceUnicode = 9816; break;
                }
                board[x + (16-4*y)] = (char)(pieceUnicode+((i==0)?6:0)); // black piece = white piece + 6
            }
        }
        System.out.print("\n" + padding + "4 ");
        for(int i = 0; i < board.length; i++){
            System.out.print(board[i]);
            if((i+1)%4 == 0 && i !=0 && i != board.length -1)
                System.out.print("\n" + padding +((16-i+1)/4) + " ");
        }
        System.out.println("\n" + padding + "  A B C D\n");
    }

Just call

debugBoard(char[][] white, char[][] black);

wherever you want and it will output the board.

Note: hackerrank is a very buggy website, so occasionally this will happen:

 4 ������������
 3 ������������
 2 ������������
 1 ������������
    A B C D

To temporarily fix this issue, it can help to add a bunch of spaces to the padding string at the top of the method. Another note: If the method is given white and black piece arrays with conflicting pieces, it will simply display the white piece. eg.

Black Piece: B B 1, White Piece: Q B 1

In this case B1 will be displayed with the white queen. Be wary of this in case your code isn't properly getting rid of taken pieces.