问题详述：Deque在Python中如何实现？

解答：

可以使用模块“ collections ” 在python中实现Deque 。双端队列优于在列表中，我们需要更快从容器的两端追加和弹出操作的情况下，如双端队列提供了一种O（1）相比于列表进行追加和弹出操作时间复杂度，其提供O（n）的时间复杂度。

deque操作：

1. append（）： - 此函数用于将参数中的值插入 deque 的右端。

2. appendleft（）： - 此函数用于将参数中的值插入 deque 的左端。

3. pop（）： - 此函数用于从双端队列的右端删除一个参数。

4. popleft（）： - 此函数用于从双端队列的左端删除一个参数。

# Python code to demonstrate working of

# append(), appendleft(), pop(), and popleft()

# importing "collections" for deque operations

import collections

# initializing deque

de = collections.deque([1,2,3])

# using append() to insert element at right end

# inserts 4 at the end of deque

de.append(4)

# printing modified deque

print ("The deque after appending at right is : ")

print (de)

# using appendleft() to insert element at right end

# inserts 6 at the beginning of deque

de.appendleft(6)

# printing modified deque

print ("The deque after appending at left is : ")

print (de)

# using pop() to delete element from right end

# deletes 4 from the right end of deque

de.pop()

# printing modified deque

print ("The deque after deleting from right is : ")

print (de)

# using popleft() to delete element from left end

# deletes 6 from the left end of deque

de.popleft()

# printing modified deque

print ("The deque after deleting from left is : ")

print (de)