java动态规划解决8皇后问题

根据引用中的描述，八皇后问题可以使用回溯法来解决。当然，也可以使用动态规划。以下是Java动态规划解决八皇后问题的代码示例[^1]：

public class EightQueenDP {
    private static final int CHESSBOARD_SIZE = 8;

    public static void main(String[] args) {
        int[][] result = eightQueen();
        printChessboard(result);
    }

    private static int[][] eightQueen() {
        int[][] chessboard = new int[CHESSBOARD_SIZE][CHESSBOARD_SIZE];
        int[] queenPos = new int[CHESSBOARD_SIZE];

        for (int i = 0; i < CHESSBOARD_SIZE; i++) {
            Arrays.fill(chessboard[i], -1);
        }

        for (int i = 0; i < CHESSBOARD_SIZE; i++) {
            int max = -1;
            int row = -1;
            for (int j = 0; j < CHESSBOARD_SIZE; j++) {
                if (queenPos[j] == 0) {
                    int count = calculateAttackCount(chessboard, i, j);
                    if (count > max) {
                        max = count;
                        row = j;
                    }
                }
            }
            chessboard[i][row] = 1;
            queenPos[row] = 1;
        }

        return chessboard;
    }

    private static int calculateAttackCount(int[][] chessboard, int row, int col) {
        int count = 0;
        for (int i = row - 1; i >= 0; i--) {
            if (chessboard[i][col] == 1) {
                count++;
            }
            if (col - row + i >= 0 && chessboard[i][col - row + i] == 1) {
                count++;
            }
            if (col + row - i < CHESSBOARD_SIZE && chessboard[i][col + row - i] == 1) {
                count++;
            }
        }
        return count;
    }

    private static void printChessboard(int[][] chessboard) {
        for (int i = 0; i < CHESSBOARD_SIZE; i++) {
            for (int j = 0; j < CHESSBOARD_SIZE; j++) {
                if (chessboard[i][j] == 1) {
                    System.out.print("Q ");
                } else {
                    System.out.print("* ");
                }
            }
            System.out.println();
        }
    }
}

这个方法使用了一个二维数组来表示棋盘，1表示该位置有皇后，-1表示该位置没有皇后。使用一维数组queenPos来表示每列是否已经放置了皇后。在每一行中，先计算每个空位置的攻击数，然后选择攻击数最大的位置来放置皇后，直到所有皇后都被放置。