Stack Concept and LIFO Principle in DSA Python - Build from Scratch

Stack Concept and LIFO Principle

📖 Scenario: Imagine you are organizing a stack of books on a table. You can only add or remove the top book. This is how a stack works in programming, following the Last In, First Out (LIFO) principle.

🎯 Goal: You will create a stack using a list, add books to it, remove the top book, and then show the final stack order.

📋 What You'll Learn

Create a list called stack with initial books

Add a new book to the top of the stack

Remove the top book from the stack

Print the final stack showing the order of books from bottom to top

💡 Why This Matters

🌍 Real World

Stacks are used in real life when you pile plates or books where you can only take the top one first.

💼 Career

Understanding stacks helps in programming tasks like undo features, expression evaluation, and managing function calls.

1

Create the initial stack

Create a list called stack with these exact books in order: 'Book1', 'Book2', 'Book3'

DSA Python

# Create the initial stack list with 'Book1', 'Book2', 'Book3'
# Your code here

Hint

Use square brackets [] to create a list and separate items with commas.

2

Add a new book to the stack

Add the book 'Book4' to the top of the stack using the append method

DSA Python

stack = ['Book1', 'Book2', 'Book3']
# Add 'Book4' to the top of the stack
# Your code here

Hint

Use stack.append('Book4') to add the new book on top.

3

Remove the top book from the stack

Remove the top book from the stack using the pop method and store it in a variable called removed_book

DSA Python

stack = ['Book1', 'Book2', 'Book3']
stack.append('Book4')
# Remove the top book and save it in 'removed_book'
# Your code here

Hint

Use removed_book = stack.pop() to remove the last added book.

4

Print the final stack

Print the stack list to show the books remaining from bottom to top

DSA Python

stack = ['Book1', 'Book2', 'Book3']
stack.append('Book4')
removed_book = stack.pop()
# Print the final stack
# Your code here

Hint

Use print(stack) to display the current stack.