java - 如何将字符串中的值分配给二维数组？

Question

我正在用 java 编写一个数独解算器，想知道如何使用 charAt 或其他东西将字符串中的值分配给二维数组？例如，这是打印板的样子:

     1  2  3    4  5  6      7  8  9      
  +-----------+-----------+-----------+
A |  0  0  0  |  0  0  5  |  0  9  0  |
B |  1  4  0  |  0  0  0  |  6  7  0  |
C |  0  8  0  |  0  0  2  |  4  5  1  |
  +-----------+-----------+-----------+
D |  0  6  3  |  0  7  0  |  0  1  0  |
E |  9  0  0  |  0  0  0  |  0  0  3  |
F |  0  1  0  |  0  9  0  |  5  2  0  |
  +-----------+-----------+-----------+
G |  0  0  7  |  2  0  0  |  0  8  0  |
H |  0  2  6  |  0  0  0  |  0  3  5  |
I |  0  0  0  |  4  0  9  |  0  6  0  |
  +-----------+-----------+-----------+

这是我迄今为止为打印板分配值的方式:

public void printBoard() {

        System.out.print("   ");
        for (int j = 0; j < 3; j++)
            System.out.print("  " + (j+1));
        System.out.print("  ");
        for (int j = 3; j < 6; j++)
            System.out.print("  " + (j+1)); 
        System.out.print("    ");
        for (int j = 6; j < 9; j++)
            System.out.print("  " + (j+1)); 
        System.out.print("      ");
        System.out.println();
        System.out.print("  +-----------+-----------+-----------+\n");
        char row_letter = 'A';
        for (int i = 0; i < 3; i++) {
            System.out.print(row_letter + " |"); 
            row_letter++;
            System.out.print("  " + board[i][0] + 
                             "  " + board[i][1] +
                             "  " + board[i][2] + "  |" + 
                             "  " + board[i][3] + 
                             "  " + board[i][4] +
                             "  " + board[i][5] + "  |" +
                             "  " + board[i][6] + 
                             "  " + board[i][7] +
                             "  " + board[i][8] + "  |");
            System.out.println("");
        }
        System.out.print("  +-----------+-----------+-----------+\n");
        for (int i = 3; i < 6; i++) {
            System.out.print(row_letter + " |"); 
            row_letter++;
            System.out.print("  " + board[i][0] + 
                             "  " + board[i][1] +
                             "  " + board[i][2] + "  |" + 
                             "  " + board[i][3] + 
                             "  " + board[i][4] +
                             "  " + board[i][5] + "  |" +
                             "  " + board[i][6] + 
                             "  " + board[i][7] +
                             "  " + board[i][8] + "  |");
            System.out.println("");
        }
        System.out.print("  +-----------+-----------+-----------+\n");
        for (int i = 6; i < 9; i++) {
            System.out.print(row_letter + " |"); 
            row_letter++;
            System.out.print("  " + board[i][0] + 
                             "  " + board[i][1] +
                             "  " + board[i][2] + "  |" + 
                             "  " + board[i][3] + 
                             "  " + board[i][4] +
                             "  " + board[i][5] + "  |" +
                             "  " + board[i][6] + 
                             "  " + board[i][7] +
                             "  " + board[i][8] + "  |");
            System.out.println("");
        }   
        System.out.print("  +-----------+-----------+-----------+\n");
    }

public static void main(String[] args) {
        int[][] board = new int[9][9];
        board[0][3] = 1;
        board[0][5] = 5;
        board[1][0] = 1;
        board[1][1] = 4;
        board[1][6] = 6;
        board[1][7] = 7;
        board[2][1] = 8;
        board[2][5] = 2;
        board[2][6] = 4;
        board[3][1] = 6;
        board[3][2] = 3;
        board[3][4] = 7;
        board[3][7] = 1;
        board[4][0] = 9;
        board[4][8] = 3;
        board[5][1] = 1;
        board[5][4] = 9;
        board[5][6] = 5;
        board[5][7] = 2;
        board[6][2] = 7;
        board[6][3] = 2;
        board[6][7] = 8;
        board[7][1] = 2;
        board[7][2] = 6;
        board[7][7] = 3;
        board[7][8] = 5;
        board[8][3] = 4;
        board[8][5] = 9;

我想知道如何使用 81 位字符串，例如 :"000005090140000670080002451063070010900000003007200080026000035000409060"给打印板的某个位置赋值，0代表未解决。

Answer 1

严格回答问题，公式

81 / 9 * row + col

只要您使用零索引的行和列，

就会为您提供字符串中代表您想要的棋盘位置的字符位置。所以类似

public String GetBoardValue(int row, int col)
{
    return boardString.CharAt(81 / 9 * row + col);
}

但要小心，这样的代码非常脆弱并且容易崩溃。此处使用的数字 81 和 9 仅在字符串长度恰好为 81 个字符时才有效。编程中的“魔数(Magic Number)”很糟糕。

正如马库斯提到的，你需要考虑一下你想在这里实现什么目标。以这种方式表示的棋盘的纯字符串没有内在值(value)或意义。至少二维数组是一种更接近数独游戏板的数据表示形式。然而，创建自己的对象来封装棋盘数据并提供特定于数独棋盘的访问器将是更好的方法。它将赋予数据意义并且更容易使用。编程的目标是编写有意义的代码，以便阅读您代码的其他人能够理解它并可以使用它。因为在很多情况下，当你有一段时间没有查看这段代码时，这个人就是几个月后的你。如果您需要花时间阅读代码才能理解您的意思，那么有更好的方法来编写它。