Queue

A queue is a linear data structure that follows the First-In, First-Out (FIFO) principle. This means the first element added is the first one to be removed.

Analogy: People in a Line

Think of a queue at:

• A bus stop
• A ticket counter
• A fast food restaurant

The first person to arrive is the first to be served, and new people join at the end of the line.

In a queue data structure, the first element added is the first one to be removed. That’s how a queue works in programming too.

The main operations on a queue are:

• Enqueue: Adds an element to the back (or “rear”) of the queue.
• Dequeue: Removes the element from the front of the queue.

from collections import deque

# Create an empty queue
queue = deque()

# Enqueue (add to end)
queue.append("Task 1")
queue.append("Task 2")
queue.append("Task 3")

print("Queue:", queue)

# Dequeue (remove from front)
first_task = queue.popleft()
print("Dequeued:", first_task)
print("Queue after dequeue:", queue)

Use Case
Print Queue	Documents are printed in the order they were added
Task Scheduling	OS or threads manage jobs/tasks using queues
Call Center Systems	Incoming calls are held in a queue
Data Streaming	Real-time processing of messages/events
Keyboard/Input Buffers	Characters typed by users are stored and processed in order

https://en.wikipedia.org/wiki/Queue_(abstract_data_type)