Double-Ended Queues in Python

The regular queue data structure follows FIFO(First in First Out) rule. Queue is a great data structure, but when it comes to adding elements at the end or removing elements from the beginning, it gets complicated.

This is where Double-Ended aka deque comes into the picture. Deque supports adding and removing elements from both ends.

Generally, deques are implemented using a doubly LinkedList. However, Python collections the built-in module has a deque class, which makes it easy to use.

Let's look at the few important functions of deque

1. Import the deque class

from collections import deque

1. Create a deque with numbers

   from collections import deque
   
   # deque with elements
   prime_numbers = deque([3,5,7,11])
   print(prime_numbers)
   

2. Append the element at the right end

prime_numbers.append(13)
print(prime_numbers) #[3, 5, 7, 11, 13]

1. Append element at the left end

prime_numbers.appendleft(2)
print(prime_numbers)# [2, 3, 5, 7, 11, 13]

1. Pop element from the right end

prime_numbers.pop() #13

1. Pop element from the left end

   prime_numbers.popleft() # 2
   

Let's see all these methods in animation.

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