You can improve that by around 13% if you soften the inequality (your > should be >=, I believe) table = {} s = 'ddddd' for i in range(100): if

You can improve that by around 13% if you soften the inequality (your > should be >=, I believe) table = {} s = 'ddddd' for i in range(100): if i%5 == 0: print(s) state = table.setdefault(s, {'f':0, 'd':0}) s = s[1:] + ('f' if state['f'] <= state['d'] > 0 else 'd') state[s[-1]] += 1