Question

In Python, ________ module needs to be imported for implementing a Double-Ended Queue?

• A. counter
• B. collections
• C. random
• D. numpy

Answer 1

The Correct Option is B

In Python, to implement a Double-Ended Queue (Deque), we need to import the collections module. The collections module provides a range of specialized container data types in addition to Python's built-in containers such as lists, dictionaries, and tuples. One of these is deque (double-ended queue), which supports thread-safe, memory-efficient appends and pops from either side of the deque with approximately the same O(1) performance in either direction.
To use a deque, you can import and initialize it as follows: 

from collections import deque
dq=deque()

With deque, you can perform operations such as append() and appendleft() for adding elements, along with pop() and popleft() for removing them from either end.

Answer 2

In Python, the collections module needs to be imported for implementing a Double Ended Queue (Deque).

Additional Context:

• Collections Module (Option 2):
  • Contains specialized container datatypes
  • Provides deque class for double-ended queues
• Deque Implementation:

  from collections import deque
  d = deque([1, 2, 3])
  d.appendleft(0)  # Add to front
  d.append(4)      # Add to end
      

• Key Features:
  • O(1) complexity for append/pop at both ends
  • Thread-safe for appends/pops
  • Max length can be specified
• Why Other Options Are Incorrect:
  • counter (1): For counting hashable objects
  • random (3): For generating random numbers
  • numpy (4): For numerical computing

Correct Answer: (2) collections.