Python3-笔记-B-006-数据结构-双向队列deque

Posted 2020-10-12

from collections import deque
# 双向队列[有序序列] (封装list)
def deques():
    # 双向队列,线程安全,队列两端添加和弹出复杂度为O(1),效率很高
    # 创建
    lists = ["A", "B", "C", "D", "E"] # <class ‘list‘>: [‘A‘, ‘B‘, ‘C‘, ‘D‘, ‘E‘]
    queue = deque(lists) # deque([‘A‘, ‘B‘, ‘C‘, ‘D‘, ‘E‘])
    queue = deque(lists, 3) # 3为限制容器大小,队列满之后,先添加的元素将挤出另一端的旧元素;
                            # 未指定容器大小将是任意长度, deque([‘C‘, ‘D‘, ‘E‘], maxlen=3)
    queue = deque(range(10)) # deque([0, 1, 2, 3, 4, 5, 6, 7, 8, 9])

    # 添加
    queue.append("F") # 添加到右边, deque([0, 1, 2, 3, 4, 5, 6, 7, 8, 9, ‘F‘])
    queue.appendleft("G") # 添加到左边, deque([‘G‘, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, ‘F‘])
    queue.extend(range(3)) # 右边添加iterable元素, deque([‘G‘, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, ‘F‘, 0, 1, 2])
    queue.extendleft(range(3)) # 追加到左边，注意变成了210，deque([2, 1, 0, ‘G‘, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, ‘F‘, 0, 1, 2])
    queue.insert(1, "L") # 在指定的index插入元素，deque([2, ‘L‘, 1, 0, ‘G‘, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, ‘F‘, 0, 1, 2])
    queue = queue + deque(range(3)) # 合并， deque([2, ‘L‘, 1, 0, ‘G‘, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, ‘F‘, 0, 1, 2, 0, 1, 2])
    queue = queue * 3 # n倍

    # 获取
    queue = deque(lists) # deque([‘A‘, ‘B‘, ‘C‘, ‘D‘, ‘E‘])
    queue2 = queue.copy() # 浅拷贝
    index = queue.index("C") # 获取索引,未找到抛ValueError异常, 2
    index = queue.index("C", 1) # 可以指定start
    index = queue.index("C", 2, 4) # 可以指定end
    elem = max(queue) # e
    elem = min(queue) #

    # 统计
    count = queue.count("A") # 1

    # 删除
    elem = queue.pop() # 弹出右边元素, deque([‘A‘, ‘B‘, ‘C‘, ‘D‘])
    elem = queue.popleft() # 弹出左边元素, deque([‘B‘, ‘C‘, ‘D‘])
    queue.remove("C") # deque([‘B‘, ‘D‘])
    queue.clear() # 清空


    # 指针
    queue = deque(lists)  # deque([‘A‘, ‘B‘, ‘C‘, ‘D‘, ‘E‘])
    queue.rotate(-1) # 旋转指针 +元素后移 -元素前移, deque([‘B‘, ‘C‘, ‘D‘, ‘E‘, ‘A‘])

    # 其他
    queue.reverse() # 反转元素, deque([‘A‘, ‘E‘, ‘D‘, ‘C‘, ‘B‘])