Why Stack Exists and What Problems It Solves in DSA Python - Test Your Knowledge

Practice - 5 Tasks

1fill in blank

easy

Complete the code to push an element onto the stack.

DSA Python

stack = []
stack.[1](5)
print(stack)

Drag options to blanks, or click blank then click option'

Ainsert

Bappend

Cremove

Dpop

Attempts:

3 left

💡 Hint

Common Mistakes

Using pop instead of append

Using remove which deletes a value

To add an element to the top of the stack, we use the append method.

2fill in blank

medium

Complete the code to remove the top element from the stack.

DSA Python

stack = [1, 2, 3]
top = stack.[1]()
print(top)
print(stack)

Drag options to blanks, or click blank then click option'

Aappend

Binsert

Cremove

Dpop

Attempts:

3 left

💡 Hint

Common Mistakes

Using append instead of pop

Using remove which deletes by value

The pop method removes and returns the last element, which is the top of the stack.

3fill in blank

hard

Fix the error in the code to check if the stack is empty.

DSA Python

stack = []
if len(stack) [1] 0:
    print('Stack is empty')
else:
    print('Stack is not empty')

Drag options to blanks, or click blank then click option'

A==

B!=

C>

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Using != which checks for not empty

Using > or < which are incorrect here

To check if the stack is empty, we compare its length to zero using ==.

4fill in blank

hard

Fill both blanks to create a stack and push an element.

DSA Python

stack = [1]
stack.[2](10)
print(stack)

Drag options to blanks, or click blank then click option'

A[]

Bappend

Cpop

D{}

Attempts:

3 left

💡 Hint

Common Mistakes

Using {} which creates a dictionary

Using pop to add elements

We create an empty list with [] and add an element using append.

5fill in blank

hard

Fill all three blanks to pop an element and check if stack is empty.

DSA Python

stack = [5, 6, 7]
top = stack.[1]()
if len(stack) [2] 0:
    print('Stack is empty after popping')
else:
    print('Stack still has elements')
print('Popped element:', [3])

Drag options to blanks, or click blank then click option'

Aappend

Bpop

C==

Dtop

Attempts:

3 left

💡 Hint

Common Mistakes

Using append instead of pop

Using != instead of ==

Printing stack instead of popped element

Use pop to remove the top element, check if length equals zero, and print the popped element stored in top.