Hello there! Today, we will unveil Queues in coding, likening them to a line in a coffee shop or a queue of print requests. Queues in computer science are First-In, First-Out (FIFO) structures. Consider this example: you're at a theme park — the first person in line for the roller coaster gets on first. Today's lesson revolves around this straightforward yet powerful concept. So, let's dive in!

In Ruby, queues can be elegantly implemented using the built-in Array class. The array functions as a flexible structure for efficiently managing queue operations. Let’s explore creating a queue using an array in Ruby:

In this example, queue is our empty array ready to be utilized as a queue.

Enqueue, a fancy term, denotes adding an item to the queue — the item lines up at the end. Here's how it plays out in our Queue class:

This sequence adds the elements 10, 20, and 30 to the queue, with 10 being at the front.

Just as Enqueue adds an element to our queue, Dequeue removes it. It extracts the element at the queue's front:

The dequeue method removes an item from the front of the queue using shift and returns it, allowing you to access the removed element.

The time complexity of enqueue and dequeue operations remains constant: O(1). However, the space complexity varies with the size of the queue, making it O(n).

As you might have noticed, both queues and stacks rely on the same underlying Array class in Ruby. Internally, both structures rely on the ability to add and remove elements, using push to add elements. The primary difference lies in element removal — queues employ shift to remove the first element (FIFO), whereas stacks use pop to remove the last element (LIFO). This subtle divergence in removal operations defines their unique behavior in data handling.

We've learned about the Queue, its operations, and its implementation in Ruby. Furthermore, these techniques are fundamental for the smooth functioning in daily life. They are invaluable and versatile in various applications, from data buffering in hardware to process scheduling in operating systems.

With your newfound knowledge of the Queue data structure, it's time to level up! Next are some practice problems to enhance your understanding of these concepts. Let's dive in!