Learn the fundamental concepts of queues, the FIFO (First In, First Out) principle, and discover how this essential data structure manages order and fairness in computing systems.

Learning Objectives

Queue Concept

Understand what a queue is and its properties

FIFO Principle

Master First In, First Out operations

Real Applications

Discover queue usage in systems and algorithms

What is a Queue?

A queue is a linear data structure that follows the First In, First Out (FIFO) principle. Think of it like a line at a store - the first person in line is the first person served.

Key Characteristics:

Linear data structure

FIFO (First In, First Out) ordering

Access from both ends (front & rear)

Dynamic size (can grow/shrink)

Queue Visualization

← Dequeue (Front)

First

Second

Third

Enqueue (Rear) →

Front element leaves first, new elements join at rear

FIFO Principle in Action

FIFO means the first element added to the queue will be the first one to be removed. This ensures fairness and order in data processing.

Enqueue Operation

Adding an element to the rear of the queue

queue.enqueue(element)

// Adds to rear

Dequeue Operation

Removing the front element from the queue

element = queue.dequeue()

// Removes from front

Step-by-Step Example

enqueue(A) → [A]

enqueue(B) → [A,B]

enqueue(C) → [A,B,C]

dequeue() → returns A

[B,C]

dequeue() → returns B

[C]

Real-World Queue Examples

Task Scheduling

CPU scheduler manages processes

Process A (first)

Process B

Process C (last)

Print Queue

Documents printed in order

Document 1 (printing)

Document 2 (waiting)

Document 3 (waiting)

Breadth-First Search

Graph traversal algorithm

Visit neighbors level by level

Queue maintains order

Web Server Requests

HTTP requests served in order

Request 1 (processing)

Request 2 (queued)

Request 3 (queued)

Buffer Management

I/O operations buffering

Data chunks

Processed in order

Memory efficient

Customer Service

Call center queue system

First caller served first

Fair service order

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