python实现八皇后问题

 import random

 def judge(state, nextX):   #判断是否和之前的皇后状态有冲突
     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 judge(state, pos):
             if len(state) == num-1:
                 yield (pos,)   #(pos,)中的逗号使其必须被设置为元组而不是简单地加上括号
             else:
                 for result in queens(num, state+(pos,)):
                     yield (pos,)+result

 def randomPrint(solution):
     for i in range(8):
         print( '•'*solution[i]+'X'+'•'*(8-solution[i]-1))

 ans = int(len(list(queens(8))))
 print(ans)
 randomPrint(random.choice(list(queens())))  #随机输出一种情况