Python基于生成器迭代实现的八皇后问题示例

　　本文实例讲述了Python基于生成器迭代实现的八皇后问题。分享给大家供大家参考，具体如下：

　　问题：有一个棋盘和8个要放到上面的皇后，唯一的要求是皇后之间不能形成威胁。也就是说，必须把他们防止成每个皇后都不能吃掉其他皇后的状态。

　　 # -*- coding: utf-8 -*- #python 2.7.13 __metaclass__ = type def confict(state, nextX): nextY = len(state) for i in range(nextY): if abs(state[i] - nextX) in (0, nextY - i): return True return False def queens(num=8, state=()): for pos in range(num): if not confict(state, pos): if len(state) == num -1: yield (pos,) else: for result in queens(num, state + (pos,)): yield (pos,) + result print list(queens()) #打印输出

　　运行结果：

　　[(0, 4, 7, 5, 2, 6, 1, 3), (0, 5, 7, 2, 6, 3, 1, 4), (0, 6, 3, 5, 7, 1, 4, 2), (0, 6, 4, 7, 1, 3, 5, 2), (1, 3, 5, 7, 2, 0, 6, 4), (1, 4, 6, 0, 2, 7, 5, 3), (1, 4, 6, 3, 0, 7, 5, 2), (1, 5, 0, 6, 3, 7, 2, 4), (1, 5, 7, 2, 0, 3, 6, 4), (1, 6, 2, 5, 7, 4, 0, 3), (1, 6, 4, 7, 0, 3, 5, 2), (1, 7, 5, 0, 2, 4, 6, 3), (2, 0, 6, 4, 7, 1, 3, 5), (2, 4, 1, 7, 0, 6, 3, 5), (2, 4, 1, 7, 5, 3, 6, 0), (2, 4, 6, 0, 3, 1, 7, 5), (2, 4, 7, 3, 0, 6, 1, 5), (2, 5, 1, 4, 7, 0, 6, 3), (2, 5, 1, 6, 0, 3, 7, 4), (2, 5, 1, 6, 4, 0, 7, 3), (2, 5, 3, 0, 7, 4, 6, 1), (2, 5, 3, 1, 7, 4, 6, 0), (2, 5, 7, 0, 3, 6, 4, 1), (2, 5, 7, 0, 4, 6, 1, 3), (2, 5, 7, 1, 3, 0, 6, 4), (2, 6, 1, 7, 4, 0, 3, 5), (2, 6, 1, 7, 5, 3, 0, 4), (2, 7, 3, 6, 0, 5, 1, 4), (3, 0, 4, 7, 1, 6, 2, 5), (3, 0, 4, 7, 5, 2, 6, 1), (3, 1, 4, 7, 5, 0, 2, 6), (3, 1, 6, 2, 5, 7, 0, 4), (3, 1, 6, 2, 5, 7, 4, 0), (3, 1, 6, 4, 0, 7, 5, 2), (3, 1, 7, 4, 6, 0, 2, 5), (3, 1, 7, 5, 0, 2, 4, 6), (3, 5, 0, 4, 1, 7, 2, 6), (3, 5, 7, 1, 6, 0, 2, 4), (3, 5, 7, 2, 0, 6, 4, 1), (3, 6, 0, 7, 4, 1, 5, 2), (3, 6, 2, 7, 1, 4, 0, 5), (3, 6, 4, 1, 5, 0, 2, 7), (3, 6, 4, 2, 0, 5, 7, 1), (3, 7, 0, 2, 5, 1, 6, 4), (3, 7, 0, 4, 6, 1, 5, 2), (3, 7, 4, 2, 0, 6, 1, 5), (4, 0, 3, 5, 7, 1, 6, 2), (4, 0, 7, 3, 1, 6, 2, 5), (4, 0, 7, 5, 2, 6, 1, 3), (4, 1, 3, 5, 7, 2, 0, 6), (4, 1, 3, 6, 2, 7, 5, 0), (4, 1, 5, 0, 6, 3, 7, 2), (4, 1, 7, 0, 3, 6, 2, 5), (4, 2, 0, 5, 7, 1, 3, 6), (4, 2, 0, 6, 1, 7, 5, 3), (4, 2, 7, 3, 6, 0, 5, 1), (4, 6, 0, 2, 7, 5, 3, 1), (4, 6, 0, 3, 1, 7, 5, 2), (4, 6, 1, 3, 7, 0, 2, 5), (4, 6, 1, 5, 2, 0, 3, 7), (4, 6, 1, 5, 2, 0, 7, 3), (4, 6, 3, 0, 2, 7, 5, 1), (4, 7, 3, 0, 2, 5, 1, 6), (4, 7, 3, 0, 6, 1, 5, 2), (5, 0, 4, 1, 7, 2, 6, 3), (5, 1, 6, 0, 2, 4, 7, 3), (5, 1, 6, 0, 3, 7, 4, 2), (5, 2, 0, 6, 4, 7, 1, 3), (5, 2, 0, 7, 3, 1, 6, 4), (5, 2, 0, 7, 4, 1, 3, 6), (5, 2, 4, 6, 0, 3, 1, 7), (5, 2, 4, 7, 0, 3, 1, 6), (5, 2, 6, 1, 3, 7, 0, 4), (5, 2, 6, 1, 7, 4, 0, 3), (5, 2, 6, 3, 0, 7, 1, 4), (5, 3, 0, 4, 7, 1, 6, 2), (5, 3, 1, 7, 4, 6, 0, 2), (5, 3, 6, 0, 2, 4, 1, 7), (5, 3, 6, 0, 7, 1, 4, 2), (5, 7, 1, 3, 0, 6, 4, 2), (6, 0, 2, 7, 5, 3, 1, 4), (6, 1, 3, 0, 7, 4, 2, 5), (6, 1, 5, 2, 0, 3, 7, 4), (6, 2, 0, 5, 7, 4, 1, 3), (6, 2, 7, 1, 4, 0, 5, 3), (6, 3, 1, 4, 7, 0, 2, 5), (6, 3, 1, 7, 5, 0, 2, 4), (6, 4, 2, 0, 5, 7, 1, 3), (7, 1, 3, 0, 6, 4, 2, 5), (7, 1, 4, 2, 0, 6, 3, 5), (7, 2, 0, 5, 1, 4, 6, 3), (7, 3, 0, 2, 5, 1, 6, 4)]

　　输出列表长度：

　　 print len(list(queens()))# 输出：92

　　更多关于Python相关内容感兴趣的读者可查看本站专题：《Python数学运算技巧总结》、《Python数据结构与算法教程》、《Python函数使用技巧总结》、《Python字符串操作技巧汇总》、《Python入门与进阶经典教程》及《Python文件与目录操作技巧汇总》

　　希望本文所述对大家Python程序设计有所帮助。