環形佇列定義

以一維陣列CQ(0 ~ n-1)表示一個環狀佇列
指標front指向佇列前端元素的前一個位置，指標rear則指向佇列尾端的元素，如下圖。

實作環形佇列

from collections import deque
##定義一8個元素環形佇列
cq = deque([11,22,33,44,55,66], maxlen=8) ##如下圖
cq.append(77)
cq.extend([88])

# [11,22,33,44,55,66,77,88]
print(cq.pop())  # [11,22,33,44,55,66,77] --> 88

# 旋轉指標
cq.rotate(-1)

# at this point you have [22,33,44,55,66,77,11]
print(cq.pop())  # [22,33,44,55,66,77] --> 11
print(cq.pop())  # [22,33,44,55,66] --> 77
print(cq.pop())  # [22,33,44,55] --> 66
print(cq.pop())  # [22,33,44] --> 55

程式執行成果