Python Coding challenge - Day 778| What is the output of the following Python Code?

 Code Explanation:

Importing deque from the collections module

from collections import deque

The deque (pronounced “deck”) is imported from Python’s built-in collections module.

It stands for Double-Ended Queue — you can efficiently add or remove elements from both ends (appendleft, append, popleft, pop).

Creating a deque with initial elements

dq = deque([10, 20, 30, 40])

Here, a deque dq is created and initialized with [10, 20, 30, 40].

Internally, it behaves like a list but with faster append and pop operations from both ends.

Current deque:

[10, 20, 30, 40]

Rotating the deque by 2 positions

dq.rotate(2)

The rotate(n) method rotates elements to the right by n steps.

Elements that go past the right end reappear on the left.

So, rotating by 2 moves the last two elements (30, 40) to the front.

After rotation:

[30, 40, 10, 20]

Adding an element to the left end

dq.appendleft(5)

appendleft() inserts a new element at the beginning of the deque.

Here, 5 is added to the left side.

Deque now:

[5, 30, 40, 10, 20]

Removing the element from the right end

dq.pop()

pop() removes the last (rightmost) element.

The element 20 is removed.

Deque after pop:

[5, 30, 40, 10]

Printing the final deque as a list

print(list(dq))

list(dq) converts the deque into a normal list for printing.

It shows the current elements in order.

Final Output:

[5, 30, 40, 10]

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