Queues

A queue is a linear data structure that follows the First-In-First-Out (FIFO) principle, meaning the first element added is the first one to be removed. Think of it like a line of people waiting - the person who arrives first gets served first.

Properties

• FIFO (First In, First Out) ordering: The first element added is the first one to be removed.
• Elements added at rear (enqueue): New elements are always added to the back of the queue.
• Elements removed from front (dequeue): Elements are always removed from the front of the queue.
• Can be implemented using arrays or linked lists: Flexible implementation options depending on needs.

Use Cases

• Print job management: Handling print requests in the order they were submitted.
• Call center systems: Managing incoming calls in the order they arrive.

Operations

• Enqueue: Add element to the rear (back) of the queue.
• Dequeue: Remove and return element from the front of the queue.

Advantages

• Fair processing (first come, first served): Ensures elements are processed in the order they arrive.
• Efficient for sequential processing: All basic operations have O(1) time complexity.
• Easy to implement: Simple structure with clear insertion and deletion points.

Disadvantages

• Limited access pattern: Can only access the front element directly.

Example

import java.util.Queue;
import java.util.LinkedList;

Queue<String> students = new LinkedList<>();

// Enqueue elements
students.offer("Jalen");
students.offer("Nawiesh");
students.offer("Rafael");

// Get queue size
System.out.println(students.size()); // Prints 3

// Accessing the front element
System.out.println(students.peek()); // Prints "Jalen"

// Dequeue elements
students.poll(); // Removes "Jalen", queue: [Nawiesh, Rafael]
students.poll(); // Removes "Nawiesh", queue: [Rafael]
System.out.println(students);