Python版八皇后问题

def conflict(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=()):
if len(state) == num-1:
for pos in range(num):
if not conflict(state, pos):
yield (pos,)
else:
for pos in range(num):
if not conflict(state, pos):
for result in queens(num, state+(pos,)):
yield (pos,)+result
def prettyprint(solution):
def line(pos,length=len(solution)):
return '. '*(pos)+'X '+'. '*(length-pos-1)
for pos in solution:
print line(pos)

import random

prettyprint(random.choice(list(queens())))