A collections.deque已针对两端的推拉进行了优化。他们甚至有专门的
rotate()方法。
from collections import dequeitems = deque([1, 2])items.append(3) # deque == [1, 2, 3]items.rotate(1) # The deque is now: [3, 1, 2]items.rotate(-1) # Returns deque to original state: [1, 2, 3]item = items.popleft() # deque == [2, 3]
