import pygame
from random import random
S=200
s=pygame.display.set_mode((S,S))
t=[[random()>0.75 for x in xrange(S)] for y in xrange(S)]
def sim(s,n):
    d={0:0,1:1,2:2,3:3,4:1,5:3,6:3,7:7,8:2,9:3,10:3,11:11,12:3,13:7,14:11,15:15}
    for y in xrange(n&1, S-1, 2):
        for x in xrange(n&1, S, 2):
            p=d[t[x][y]*8+t[(x+1)%S][y]*4+t[x][y+1]*2+t[(x+1)%S][y+1]]
            t[x][y]=(p&8)!=0
            t[(x+1)%S][y]=(p&4)!=0
            t[x][y+1]=(p&2)!=0
            t[(x+1)%S][y+1]=p&1
            s.set_at((x,y),(255*(p&8!=0),)*3)
            s.set_at(((x+1)%S,y),(255*(p&4!=0),)*3)
            s.set_at((x,y+1),(255*(p&2!=0),)*3)
            s.set_at(((x+1)%S,y+1),(255*(p&1!=0),)*3)
n=0
while True:
    sim(s,n)
    n+=1
    pygame.display.flip()
    if pygame.event.poll().type==pygame.KEYDOWN: break