编辑代码

import java.util.Arrays;

public class EightQueens {
    public static void solveNQueens() {
        int[] queenPos = new int[8];
        Arrays.fill(queenPos, -1);
        placeQueen(queenPos, 0);
    }

    private static void placeQueen(int[] queenPos, int row) {
        if (row == 8) {
            printSolution(queenPos);
            return;
        }
        for (int col = 0; col < 8; col++) {
            if (isValid(queenPos, row, col)) {
                queenPos[row] = col;
                placeQueen(queenPos, row + 1);
                queenPos[row] = -1; // 回溯
            }
        }
    }

    private static boolean isValid(int[] queenPos, int row, int col) {
        for (int i = 0; i < row; i++) {
            if (queenPos[i] == col || Math.abs(i - row) == Math.abs(queenPos[i] - col)) {
                return false;
            }
        }
        return true;
    }

    private static void printSolution(int[] queenPos) {
        for (int i = 0; i < 8; i++) {
            for (int j = 0; j < 8; j++) {
                if (queenPos[i] == j) {
                    System.out.print("Q ");
                } else {
                    System.out.print("* ");
                }
            }
            System.out.println();
        }
        System.out.println();
    }

    public static void main(String[] args) {
        solveNQueens();
    }
}