Understanding Stacks: A Simple Guide

A stack is a type of data structure. Think of it like a pile of plates. The last plate you put on the top is the first one you take off. This idea is called Last In, First Out, or LIFO for short.

There are two main actions you can do with a stack: push and pop. Let’s take a closer look at what these mean.

What is the Push Operation?

Push means to add something to the top of the stack. Here’s how it works:

1. Check for Overflow: First, make sure there’s room in the stack.
2. Insert the Element: Place the new item at the top.
3. Update the Top: Move up the pointer or marker that shows where the top of the stack is.

For example, if you push the number 5 onto an empty stack, the stack now looks like this: [5].

What is the Pop Operation?

Pop means to remove the item from the top of the stack. Here’s what you do:

1. Check for Underflow: First, make sure the stack isn’t empty.
2. Retrieve the Top Element: Look at what’s on the top.
3. Remove the Element: Move the pointer down to show the new top of the stack.

For instance, if the stack has [5, 3, 8] and you pop an item, you will take off the 8. Now the stack looks like this: [5, 3].

Where Are Stacks Used?

Stacks are very useful in many areas, including:

• Function Call Management: They help keep track of which functions are running and their local information.
• Expression Evaluation: Stacks help in checking math expressions and managing operations.
• Backtracking Algorithms: They track different states in processes like depth-first search.

In short, push and pop are essential actions for working with stacks, which follow the LIFO rule. Stacks play a big role in computer science!