Queue in Python
Understand queue (FIFO) using deque, why lists are not ideal for queues, and build a simple task queue like real apps.
A **queue** follows FIFO: First In, First Out. Real examples: - ticketing systems - print queues - job scheduling - message processing ## Why not use list for queue? Removing from front of list can be slow. `collections.deque` is designed for fast ends. ## Queue with deque ```python from collections import deque q = deque() q.append("Task1") # enqueue q.append("Task2") print(q) first = q.popleft() # dequeue print(first) print(q) ``` ## Example: task processing simulation ```python from collections import deque tasks = deque(["email", "report", "backup"]) while tasks: task = tasks.popleft() print("Processing:", task) ``` ## Graph: queue FIFO ```mermaid flowchart LR A[Enqueue] --> B[Queue] --> C[Dequeue] ``` ## Remember - Use deque for queues - append + popleft - queues are everywhere in systems