# -*- coding:utf-8 -*-
__author__ = "tyomcat"

print("******八皇后问题的解决方法******")
def next_col(current, n=8):  
    length = len(current)  
    if length == n:
        return
    dangerous = current + [item for l in [(val + length - i, val - length + i)  for i, val in enumerate(current)]  for item in l if item >= 0 and item <= n]  
    for i in range(n):
            if i not in dangerous:  
                yield i  

def queens(n=8, columns=[]):  
    if len(columns) == n:  
        yield columns  
    for i in next_col(columns, n):  
        appended = columns + [i]  
        for c in queens(n, appended):  
            yield c  
 
def prettyprint(solution):  
   def line(pos,lengh=len(solution)):  
       return ‘.‘*(pos)+‘X‘+‘.‘*(lengh-pos-1)  
   for pos in solution:  
        print(line(pos))  
 
if __name__ == ‘__main__‘:  
    i = 0  
    for solution in queens(8):  
    # print(i, solution)   
        i+=1  
        if i > 1: print (‘\n‘)
        print (‘第‘ + str(i) + ‘解‘)
        prettyprint(solution)