# 【8*8棋盘八皇后问题】

 class Queen:

     def __init__(self, row, col):

         self.row = row

         self.col = col

         self.pos = (row + 1, col + 1)

     def check(self, chess_board):

         '''检查当前位置是否可放置皇后，默认每行只放一个皇后'''

         # 检测列

         for i in range(8):

             if chess_board.board[i][self.col] == 0:

                 return False

         # 检测两个斜向

         for i in range(-7, 8):

             if 0 <= self.row + i < 8 and 0 <= self.col + i < 8 and chess_board.board[self.row + i][self.col + i] == 0:

                 return False

             elif 0 <= self.row + i < 8 and 0 <= self.col - i < 8 and chess_board.board[self.row + i][self.col - i] == 0:

                 return False

         return True

 class Chess_Board:

     # 棋盘  无皇后为1，有皇后为0

     board = [[1 for i in range(8)] for i in range(8)]

     def print_board(self):

         '''可视化打印棋盘'''

         print('---------------------------------')

         for i in range(8):

             for j in range(8):

                 if self.board[i][j] == 1:

                     print(' +', end='') # + 无皇后

                 else:

                     print(' @', end='') # @ 表示皇后

             print()

         print('---------------------------------')

 def solve():

     '''返回结果棋盘对象和皇后对象列表'''

     def check_nextline(queens, chess_board):

         '''已知所有皇后坐标，判断下一行是否有位置'''

         next_col = len(queens)

         if next_col < 8:

             for i in range(8):

                 queen = Queen(next_col, i)

                 if queen.check(chess_board):

                     queens.append(queen)

                     chess_board.board[queen.row][queen.col] = 0

                     # chess_board.print_board() # 监控实现过程

                     return True

         return False

     queens = [] # 存储已放到棋盘上的皇后对象的列表

     chess_board = Chess_Board() # 创建唯一棋盘对象

     queen = Queen(0, 0)

     queens.append(queen)

     chess_board.board[queen.row][queen.col] = 0

     while 1:

         # 如果下一行没有位置，就将该行的皇后向右移一格

         while not check_nextline(queens, chess_board):

             queen = queens.pop(-1)

             chess_board.board[queen.row][queen.col] = 1

             while queen.col == 7:

                 queen = queens.pop(-1)

                 chess_board.board[queen.row][queen.col] = 1

             queen = Queen(queen.row, queen.col + 1)

             # 如果皇后右移后与原先皇后冲突，则继续右移

             while not queen.check(chess_board):

                 if queen.col < 7:

                     queen = Queen(queen.row, queen.col + 1)

                 else:

                     while queen.col == 7:

                         queen = queens.pop(-1)

                         chess_board.board[queen.row][queen.col] = 1

                     queen = Queen(queen.row, queen.col + 1)

             queens.append(queen)

             chess_board.board[queen.row][queen.col] = 0

         # 放满8个皇后之后跳出while 1循环

         if len(queens) == 8:

             break

     return queens, chess_board

 def main():

     '''主函数'''

     queens, chess_board = solve()

     for queen in queens:

         print(queen.pos)

     chess_board.print_board()

 if __name__ == "__main__":

     main()