Code Explanation:
🔹 1. Importing deque
from collections import deque
✅ Explanation:
deque stands for Double Ended Queue.
It is available in Python's collections module.
It allows insertion and deletion from both ends efficiently.
Think of it like:
Front ← [ deque ] → Back
Unlike a normal list, operations at the beginning are very fast.
🔹 2. Creating a Deque
d = deque([1, 2, 3])
✅ Explanation:
A deque object is created.
Current deque:
Front
↓
[1, 2, 3]
↑
Back
Memory:
deque([1, 2, 3])
🔹 3. Adding Element at Left Side
d.appendleft(0)
✅ Explanation:
appendleft() inserts an element at the beginning.
Current deque:
Before:
[1, 2, 3]
After:
[0, 1, 2, 3]
Visual:
0 ← inserted here
[0, 1, 2, 3]
🔹 4. Current State
After:
d.appendleft(0)
Deque becomes:
deque([0, 1, 2, 3])
🔹 5. Removing Last Element
d.pop()
✅ Explanation:
pop() removes the last element from the deque.
Current deque:
Before:
[0, 1, 2, 3]
Last element:
3
gets removed.
After:
[0, 1, 2]
🔹 6. Current State After Pop
Deque becomes:
deque([0, 1, 2])
Visual:
Front
↓
[0, 1, 2]
↑
Back
🔹 7. Converting Deque to List
list(d)
✅ Explanation:
Converts deque into a normal Python list.
Before:
deque([0, 1, 2])
After:
[0, 1, 2]
🔹 8. Printing Result
print(list(d))
Prints:
[0, 1, 2]
🎯 Final Output
[0, 1, 2]
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