八皇后啟發式

Question

我正在開發一種啟發式方法，可以將8個皇后放在8x8的棋盤上。 每個方格都有其自己的消除編號（以指示如果在一個方格中放置了一個皇后棋子，則將“消除”一個空棋盤的多少個方塊。）並且每個方格都應放置在消除號最低的方格中。

我的問題是我不知道該怎么做才能繼續減少其適當平方的特定消除數，因此，如果您能幫助我，我將非常感激。 另一個問題，我覺得我的代碼很復雜，因此有什么注釋可以使其更簡單嗎？

這是我的代碼

public class Queen {
private final int SIZE = 8;
private int board[][] = new int[SIZE][SIZE]; // 8x8 board
private int hor[] = new int[SIZE]; // horizontal moves
private int ver[] = new int[SIZE]; // vertical moves
private int lowestValue = 22;
private int[][] queens = new int[SIZE][2]; // 8 queens 

public Queen () {
    // initialize each square with its own elimination number
    for (int row = 0; row < board.length; row++) {
        for (int col = 0; col < board[row].length; col++) {
            if (row == 0 || row == 7 || ((row >= 1 && row <= 6) && (col == 0 || col == 7))) {
                board[row][col] = 22;
            } 
            else if ((row == 1 || row == 6) && (col >= 1 && col <= 6) || (row > 1 && row < 6) && (col == 1 || col == 6)) {
                board[row][col] = 24;
            }
            else if ((row == 2 || row == 5) && (col >= 2 && col <= 5)|| (row > 2 && row < 5) && (col == 2 || col == 5)){
                board[row][col] = 26;
            }
            else if ((row == 3 || row == 4) && (col >= 3 && col <= 4)){
                board[row][col] = 28;
            }

        }
    }// end initializing

    // initialize moves
    //right
    hor[0] = 1;
    ver[0] = 0;
    //left
    hor[1] = -1;
    ver[1] = 0;
    //up
    hor[2] = 0;
    ver[2] = -1;
    //down
    hor[3] = 0;
    ver[3] = 1;
    //up right
    hor[4] = 1;
    ver[4] = -1;
    hor[7] = -1;
    ver[7] = 1;
    //up left
    hor[5] = -1;
    ver[5] = -1;
    //down right
    hor[6] = 1;
    ver[6] = 1;
    // down left

    for (int queen = 0; queen < queens.length; queen++) {
        placeQueens(queen);
    }
    displayBoard();
}// end constructor

// eliminate squares according to the place of the queen
private void eliminate (int queen_row, int queen_col) {

    // eliminate diagonal
    int rowCopy = queen_row;// helper row
    int colCopy = queen_col;// helper column
    try {
        // eliminate up right
        for (int move = 0; move < 8; move++) {
            rowCopy += ver[4];
            colCopy += hor[4];
            if (board[rowCopy][colCopy] > 0) {
                board[rowCopy][colCopy] = 0;
            }
        }
    } 
    catch (ArrayIndexOutOfBoundsException e) {      
    }

    try {
        rowCopy = queen_row;
        colCopy = queen_col;
        // eliminate up left
        for (int move = 0; move < 8; move++) {
            rowCopy += ver[5];
            colCopy += hor[5];
            if (board[rowCopy][colCopy] > 0) {
            board[rowCopy][colCopy] = 0;
            }
        }
    } 
    catch (ArrayIndexOutOfBoundsException e) {
    }

    try {
        rowCopy = queen_row;
        colCopy = queen_col;
        // eliminate down right
        for (int move = 0; move < 8; move++) {
            rowCopy += ver[6];
            colCopy += hor[6];
            if (board[rowCopy][colCopy] > 0) {
            board[rowCopy][colCopy] = 0;
            }
        }
    } 
    catch (ArrayIndexOutOfBoundsException e) {
    }
    try {
        rowCopy = queen_row;
        colCopy = queen_col;
        // eliminate down left
        for (int move = 0; move < 8; move++) {
            rowCopy += ver[7];
            colCopy += hor[7];
            if (board[rowCopy][colCopy] > 0) {
            board[rowCopy][colCopy] = 0;
            }
        }
    } 
    catch (ArrayIndexOutOfBoundsException e) {
    }

    // eliminate row
    for (int col = 0; col < 8;col++) {
        if (board[queen_row][col] > 0) {
        board[queen_row][col] = 0;
        }
    }
    // eliminate col
    for (int row = 0; row < 8; row++) {
        if (board[row][queen_col] > 0) {
        board[row][queen_col] = 0;
        }
    }

}// end elimination

// decrease elimination number of each square
public void decreaseElimination () {


}// end decrease elimination

public void countEliminated () {
    int counter = 0;
    for (int row = 0; row < board.length; row++) {
        for (int col = 0; col < board[row].length; col++) {
            if (board[row][col] == 0) {
                counter++;
            }

        }
    }
    System.out.printf("%d squares eliminated\n", counter);

}

public void placeQueens(int queenNum) {
    int targetRow;
    int targetCol;
    // find lowest elimination number
    for (int row = 0; row < board.length; row++) {
        for (int col = 0; col < board[row].length; col++) {
            if (board[row][col] > 0 && board[row][col] < lowestValue) {
                lowestValue = board[row][col];
                targetRow = row;
                targetCol = col;

                queens[queenNum][0] = targetRow;
                queens[queenNum][1] = targetCol;
            }
        }
    }

    System.out.printf("queen %d has been placed in [%d][%d]\n", queenNum + 1, queens[queenNum][0], queens[queenNum][1]);
    eliminate(queens[queenNum][0], queens[queenNum][1]);
    decreaseElimination();
    countEliminated();

}

// display board
public void displayBoard () {

    for (int row = 0; row < board.length; row++) {
        for (int col = 0; col < board[row].length; col++) {
                System.out.printf("|%2d|", board[row][col]); // display elimination number of each square
        }
        System.out.println();
    }

}// end displayBoard

}

我的主要方法是在單獨的類中。

Answer 1

這段代碼天生就有缺陷：

for (int queen = 0; queen < queens.length; queen++) {
    placeQueens(queen);
}

您不能決定將皇后區0放到哪里，而又不決定確切地將皇后區1至8放到哪里。 您已實現“首次試穿”：

如上例所示，First Fit無法提供可行的解決方案。 本手冊中的更多信息（包括有效的算法）。

這是一種有效的算法（但可伸縮）：