Queue vs Stack When to Use Which in DSA Python - Build Both Approaches

Queue vs Stack: When to Use Which

📖 Scenario: Imagine you are managing a line at a coffee shop and a stack of plates in the kitchen. You want to understand how to use a queue and a stack to organize these tasks properly.

🎯 Goal: You will create a queue and a stack using Python lists, add items to each, and then remove items to see how they behave differently. This will help you understand when to use a queue or a stack.

📋 What You'll Learn

Create a queue list with specific customers in order

Create a stack list with specific plates in order

Add a new customer to the queue and a new plate to the stack

Remove one customer from the queue and one plate from the stack

Print the final state of both the queue and the stack

💡 Why This Matters

🌍 Real World

Queues are used in real life when people wait in line, like at a coffee shop or bank. Stacks are used when you stack plates or books and take from the top.

💼 Career

Understanding queues and stacks helps in programming tasks like managing tasks, undo features, and breadth-first or depth-first searches.

1

Create the initial queue and stack

Create a list called queue with these exact customers in order: 'Alice', 'Bob', 'Charlie'. Also create a list called stack with these exact plates in order: 'Plate1', 'Plate2', 'Plate3'.

DSA Python

# Create the queue and stack lists with the given items
# Your code here

Hint

Use square brackets to create lists and separate items with commas.

2

Add a new customer to the queue and a new plate to the stack

Add 'David' to the end of the queue list using the append() method. Also add 'Plate4' to the end of the stack list using the append() method.

DSA Python

queue = ['Alice', 'Bob', 'Charlie']
stack = ['Plate1', 'Plate2', 'Plate3']
# Add 'David' to queue and 'Plate4' to stack
# Your code here

Hint

Use list.append(item) to add an item to the end of a list.

3

Remove one customer from the queue and one plate from the stack

Remove the first customer from the queue list using pop(0). Remove the last plate from the stack list using pop() without arguments.

DSA Python

queue = ['Alice', 'Bob', 'Charlie']
stack = ['Plate1', 'Plate2', 'Plate3']
queue.append('David')
stack.append('Plate4')
# Remove first customer from queue and last plate from stack
# Your code here

Hint

Use pop(0) to remove the first item from a list (queue behavior) and pop() to remove the last item (stack behavior).

4

Print the final state of the queue and stack

Print the queue list and then print the stack list to show their final states after the removals.

DSA Python

queue = ['Alice', 'Bob', 'Charlie']
stack = ['Plate1', 'Plate2', 'Plate3']
queue.append('David')
stack.append('Plate4')
queue.pop(0)
stack.pop()
# Print the final queue and stack
# Your code here

Hint

Use print() to display the lists.