Stack Implementation Using Array in DSA Python - Build from Scratch

Stack Implementation Using Array

📖 Scenario: Imagine you are managing a stack of books on a table. You can only add or remove the top book. This is like a stack data structure where the last item added is the first one removed.

🎯 Goal: You will build a simple stack using a Python list (array). You will add items (push), remove the top item (pop), and see the current stack.

📋 What You'll Learn

Create an empty list called stack to hold stack items.

Create a variable called max_size and set it to 5 to limit stack size.

Write a function push(item) to add item to stack only if it is not full.

Write a function pop() to remove and return the top item from stack if it is not empty.

Print the final state of stack after some push and pop operations.

💡 Why This Matters

🌍 Real World

Stacks are used in many places like undo features in apps, browser history, and managing tasks in order.

💼 Career

Understanding stack implementation helps in software development, debugging, and preparing for coding interviews.

1

Create an empty stack

Create an empty list called stack to hold the stack items.

DSA Python

# Create an empty list called stack
# Your code here

Hint

Use [] to create an empty list in Python.

2

Set the maximum stack size

Create a variable called max_size and set it to 5 to limit the stack size.

DSA Python

stack = []
# Create max_size variable and set it to 5
# Your code here

Hint

Just assign the number 5 to the variable max_size.

3

Write push and pop functions

Write a function called push(item) that adds item to stack only if the length of stack is less than max_size. Also write a function called pop() that removes and returns the last item from stack if it is not empty; otherwise, return None.

DSA Python

stack = []
max_size = 5

# Write push(item) function
# Write pop() function
# Your code here

Hint

Use len(stack) to check size. Use stack.append(item) to add. Use stack.pop() to remove last item.

4

Test stack operations and print final stack

Use push to add 10, 20, 30 to stack. Then use pop() once. Finally, print the stack.

DSA Python

stack = []
max_size = 5

def push(item):
    if len(stack)  0:
        return stack.pop()
    else:
        return None

# Push 10, 20, 30
# Pop once
# Print the stack
# Your code here

Hint

After pushing 10, 20, 30 and popping once, the stack should have 10 and 20 left.