我正在解决一个在初级程序员中似乎有点出名的问题，即 8 个皇后难题。我已经看到了使用二维数组、递归等解决这个问题的几种方法，但是这个问题是CS课程书籍介绍一维数组的章节中给出的作业，所以解决这个问题的可用技术是有限的。
我使用的过程是首先创建一个大小为 64 的一维数组，这使得可以放置从索引 0 到 63 的皇后。然后生成随机位置索引，并执行测试以检查是否存在任何皇后攻击这个位置。如果该位置没有受到任何皇后的攻击，则通过设置board[position] = true。当女王被放置时，queenCount递增，重复此过程，直到放置了 8 个皇后。
如果皇后的放置方式无法放置 8 个皇后，则棋盘会在 1 毫秒后通过执行时间检查来重置，并重试放置 8 个皇后。我最多能放置 7 个皇后，但最后一个却从未放置过。每次尝试都会被打印出来，以及queenCount对于这次尝试。是否可以使用这种方法，或者这是一个死胡同？
代码示例如下：
package ch7;
public class Chapter_07_E22_EightQueens64bool {
public static void main(String[] args) {
int queenCount = 0;
int attemptCount = 0;
boolean[] board = new boolean[8 * 8];
final long TIME_LIMIT = 1; //Milliseconds
long startTime = System.currentTimeMillis();
while (queenCount < 8) {
int position = placeQueen(board.length);
if(checkPosition(position, board) && !board[position]) {
board[position] = true;
queenCount++;
}
long timeCheck = System.currentTimeMillis();
if (timeCheck - startTime > TIME_LIMIT) {
clearBoard(board);
queenCount = 0;
startTime = System.currentTimeMillis();
}
System.out.println("Attempt #" + ++attemptCount);
System.out.println(queenCount + " queens placed.");
printBoard(board);
}
}
public static void printBoard(boolean[] board) {
for (int i = 0; i < board.length; i++) {
if (board[i])
System.out.print("|Q");
else
System.out.print("| ");
if ((i + 1) % 8 == 0)
System.out.println("|");
}
}
public static int placeQueen(int boardSize) {
return (int)(Math.random() * boardSize);
}
public static boolean[] clearBoard(boolean[] board) {
for (int i = 0; i < board.length; i++)
board[i] = false;
return board;
}
public static boolean checkPosition(int position, boolean[] board) {
return checkTop(position, board) && checkBottom(position, board) && checkLeft(position, board) &&
checkRight(position, board) && checkTopLeft(position, board) && checkTopRight(position, board) &&
checkBottomLeft(position, board) && checkBottomRight(position, board);
}
public static boolean checkTop(int position, boolean[] board) {
// Checks each field above the current position while i >= 8
for (int i = position; i >= 8; i -= 8) {
if (board[i - 8])
return false;
}
return true;
}
public static boolean checkBottom(int position, boolean[] board) {
// Checks each field below the current position while i <= 55;
for (int i = position; i <= 55; i += 8) {
if (board[i + 8])
return false;
}
return true;
}
public static boolean checkRight(int position, boolean[] board) {
// Checks each field to the right of the current position while i % 8 < 7
for (int i = position; i % 8 < 7; i += 1) {
if (board[i + 1])
return false;
}
return true;
}
public static boolean checkLeft(int position, boolean[] board) {
// Checks each field to the left of the current position while i % 8 != 0
for (int i = position; i % 8 != 0; i -= 1) {
if (board[i - 1])
return false;
}
return true;
}
public static boolean checkTopLeft(int position, boolean[] board) {
// Checks each field top left of the current position while i >= 9
for (int i = position; i >= 9; i -= 9) {
if (board[i - 9])
return false;
}
return true;
}
public static boolean checkTopRight(int position, boolean[] board) {
// Checks each field top right of the current position while i >= 7
for (int i = position; i >= 7; i -= 7) {
if (board[i - 7])
return false;
}
return true;
}
public static boolean checkBottomRight(int position, boolean[] board) {
// Checks each field below the current position while i <= 54
for (int i = position; i <= 54; i += 9) {
if (board[i + 9])
return false;
}
return true;
}
public static boolean checkBottomLeft(int position, boolean[] board) {
// Checks each field below the current position while i <= 56
for (int i = position; i <= 56; i += 7) {
if (board[i + 7])
return false;
}
return true;
}
}
