java - 无法在列表中生成随机分散的真值和假值

Question

我正在用 Java 设计一款扫雷游戏，但我在生成哪些方 block 是地雷/不是地雷时遇到了麻烦。这是到目前为止我的代码:

import java.util.regex.Matcher;
import java.util.regex.Pattern;
import java.util.Random;
import java.util.Scanner;

public class MineSweeper {
    private final boolean[][] mines;
    public char[][] field;

    public MineSweeper(int x, int y, int numMines) {
        field = new char[x][y];

        boolean[][] tmpMines = new boolean[x][y];

        Random rand = new Random();

        // Here is where I need to use rand to evenly disperse mines across 
        // the `tmpMines` array...

        for (int i = 0; i < x; i++)
            for (int j = 0; j < y; j++) {
                field[i][j] = 'X';
            }

        mines = tmpMines;
    }

    public void showFor(int x, int y) {
        int count = 0;

        for (int[] i : new int[][]{ /* Sides */ {x + 1, y}, {x - 1, y}, {x, y - 1}, {x, y + 1}, /* Corners */ {x + 1, y + 1}, {x - 1, y -1}, {x + 1, y - 1}, {x - 1, y + 1}}) {
            try {
                if (mines[i[0]][i[1]] == true)
                    count++;
            } catch (ArrayIndexOutOfBoundsException ex) {
                // Easiest way to handle overflow.
            }
        }

        field[x][y] = Integer.toString(count).charAt(0);
    }

    private static void printCharMatrix(char[][] matrix) {
        for (char[] a : matrix) {
            for (char c : a) {
                System.out.print(c + " ");
            }
            System.out.println();
        }
    }

    private static void printBoolMatrix(boolean[][] matrix) {
        for (boolean[] a : matrix) {
            for (boolean b : a) {
                if (b == true)
                    System.out.print("X ");
                else
                    System.out.print("O ");
            }
            System.out.println();
        }
    }

    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        String input;

        Pattern patt = Pattern.compile("^\\s*(\\d+)\\s*,\\s*(\\d+)\\s*$"); // Matches any number of spaces, a digit, spaces, a comma, spaces, and a digit and extracts the 2 digits

        System.out.println("*** Welcome to MineSweeper(tm)!!! ***");
        System.out.println();
        System.out.print("Enter the number of columns: ");
        int x = scan.nextInt();
        System.out.print("Enter the number of rows: ");
        int y = scan.nextInt();
        System.out.print("Enter the number of mines: ");
        int mines = scan.nextInt();
        MineSweeper ms = new MineSweeper(x, y, mines);

        scan.nextLine();

        while (true) {
            System.out.println("Board:");
            printCharMatrix(ms.field);
            System.out.print("Type an array index (ex: 1,1). 'quit' to quit: ");
            input = scan.nextLine().toLowerCase();

            if (input.equalsIgnoreCase("quit"))
                System.exit(0);

            Matcher match = patt.matcher(input);

            if (match.find()) {
                x = Integer.parseInt(match.group(1));
                y = Integer.parseInt(match.group(2));
                if (ms.mines[x][y] == true) {
                    System.out.println("You failed!");
                    System.out.println("The board was: ");
                    System.out.println();
                    printBoolMatrix(ms.mines);
                    System.exit(0);
                } else {
                    ms.showFor(x, y);
                }
            } else {
                System.out.println("Invalid input: " + input);
            }
        }
    }
}

我需要做的是将地雷均匀地分布在地雷上(如果是地雷则为true，如果不是地雷则为false)提供的地雷数量和矩阵大小 (x * y)。我尝试了几种策略，但没有一个有效。谢谢!

Answer 1

您可以使用 numMines true 和 x*y-numMines false 填充 tmpMines 数组，并对其使用shuffle 算法。

有多种随机播放算法可以实现此目的，例如，您可能需要使用 this answer像这样打乱你的二维数组。

// fill tmpMines array
for(int i = 0; i < x; i++) {
    for (int j = 0; j < y; j++) {
        if (numMines > 0) {
            numMines--;
            tmpMines[i][j] = true;
        } else {
            tmpMines[i][j] = false;
        }
    }
}
// shuffle tmpMines array
for(int i = 0; i < x; i++) {
    for (int j = 0; j < y; j++) {
        // int swapPos = rand.nextInt(x*y);  this swapPos selection is not correct, please use the code next line.
        int swapPos = x*y - rand.nextInt(x*y-i*y+j);
        int swapPosY = swapPos / x;
        int swapPosX = swapPos % x;

        boolean tmp = tmpMines[i][j];
        tmpMines[i][j] = tmpMines[swapPosX][swapPosY];
        tmpMines[swapPosX][swapPosY] = tmp;
    }
}

我这里直接使用并修改了numMines，因为这段代码之后就不会再使用了。如果您希望 numMines 不被修改，请使用临时变量。

附:您的列和行在代码中混合在一起(当我的输入显示 7 行时，我得到 7 列)。使用二维数组时请注意它们。