Push Operation on Stack in DSA Python - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to push an element onto the stack.

DSA Python

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

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

Aappend

Bpop

Cremove

Dinsert

Attempts:

3 left

💡 Hint

Common Mistakes

Using pop instead of append removes an element instead of adding.

Using remove tries to delete a specific value, not add one.

The append method adds an element to the end of the list, which is the top of the stack.

2fill in blank

medium

Complete the code to push multiple elements onto the stack using a loop.

DSA Python

stack = []
for i in range(3):
    stack.[1](i)
print(stack)

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

Aclear

Bpop

Cappend

Dextend

Attempts:

3 left

💡 Hint

Common Mistakes

Using pop removes elements instead of adding.

Using extend expects an iterable, not a single element.

Inside the loop, append adds each number to the stack one by one.

3fill in blank

hard

Fix the error in the push operation code.

DSA Python

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

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

Aappend

Binsert

Cadd

Dpush

Attempts:

3 left

💡 Hint

Common Mistakes

Using push causes an AttributeError because lists don't have this method.

Using add is for sets, not lists.

Python lists do not have a push method; use append to add elements.

4fill in blank

hard

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

DSA Python

stack = [1]
element = 7
stack.[2](element)
print(stack)

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

A[]

Bappend

Cpop

D{}

Attempts:

3 left

💡 Hint

Common Mistakes

Using {} creates an empty dictionary, not a list.

Using pop removes elements instead of adding.

Use [] to create an empty list as a stack and append to push an element.

5fill in blank

hard

Fill all three blanks to push elements 1, 2, and 3 onto the stack.

DSA Python

stack = [1]
stack.[2](1)
stack.[3](2)
stack.append(3)
print(stack)

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

A[]

Bappend

D{}

Attempts:

3 left

💡 Hint

Common Mistakes

Using {} creates a dictionary, not a stack.

Using pop removes elements instead of adding.

Create an empty list with [] and use append to push each element.

Practice

1. What does the push operation do in a stack?

easy

A. Checks if the stack is empty

B. Removes the top element from the stack

C. Returns the bottom element of the stack

D. Adds an element to the top of the stack

Solution

1. Step 1: Understand stack behavior

   A stack follows Last In First Out (LIFO) principle, so new elements are added on top.

2. Step 2: Define push operation

   Push means adding a new element on the top of the stack.

3. Final Answer:

   Adds an element to the top of the stack -> Option D

4. Quick Check:

   Push = Add top element [OK]

Hint: Push always adds element on top of stack [OK]

Common Mistakes:

• Confusing push with pop operation
• Thinking push removes elements
• Mixing stack with queue operations

2. Which of the following is the correct syntax to push an element 5 into a stack named stack implemented as a Python list?

easy

A. stack.append(5)

B. stack.push(5)

C. stack.add(5)

D. stack.insert(0, 5)

Solution

1. Step 1: Recall Python list methods for stack

   Python lists use append() to add elements at the end, which acts as top of stack.

2. Step 2: Check each option

   push() and add() are not list methods; insert(0, 5) adds at bottom, not top.

3. Final Answer:

   stack.append(5) -> Option A

4. Quick Check:

   Use append() to push in Python list stack [OK]

Hint: Use append() to push in Python list stack [OK]

Common Mistakes:

• Using push() which is not a Python list method
• Using insert(0, value) which adds at bottom
• Confusing add() with append()

3. What will be the content of the stack after executing the following code?

stack = []
stack.append(10)
stack.append(20)
stack.append(30)

medium

A. [20, 10, 30]

B. [30, 20, 10]

C. [10, 20, 30]

D. [10, 30, 20]

Solution

1. Step 1: Trace each append operation

   Start with empty list. Append 10 -> [10], append 20 -> [10, 20], append 30 -> [10, 20, 30].

2. Step 2: Understand stack order

   Elements are added at the end; top is last element (30).

3. Final Answer:

   [10, 20, 30] -> Option C

4. Quick Check:

   Stack after pushes = [10, 20, 30] [OK]

Hint: Append adds at end; last element is top [OK]

Common Mistakes:

• Reversing the order of elements
• Confusing stack top with bottom
• Assuming append adds at start

4. Identify the error in the following code that tries to push an element 15 into a stack implemented as a list:

stack = [5, 10]
stack.push(15)

medium

A. Missing import statement for stack

B. Using push() method which does not exist for list

C. Stack should be initialized as a tuple

D. Using append() instead of push()

Solution

1. Step 1: Check list methods for adding elements

   Python lists do not have a push() method; they use append().

2. Step 2: Analyze the code error

   Calling stack.push(15) will cause an AttributeError because push is undefined.

3. Final Answer:

   Using push() method which does not exist for list -> Option B

4. Quick Check:

   List has append(), not push() [OK]

Hint: Use append() for list push, not push() [OK]

Common Mistakes:

• Assuming push() exists for Python lists
• Thinking stack must be tuple
• Ignoring AttributeError on push()

5. Given a stack implemented as a list, how would you push multiple elements [1, 2, 3] onto the stack so that 3 is on top after all pushes?

hard

A. Use a loop to append elements in order: 1, then 2, then 3

B. Use a loop to append elements in reverse order: 3, then 2, then 1

C. Use extend() method with reversed([1, 2, 3])

D. Insert elements at index 0 in order: 1, then 2, then 3

Solution

1. Step 1: Understand stack push order

   To have 3 on top, push 1 first, then 2, then 3 so 3 is last pushed.

2. Step 2: Analyze each option

   Loop append in order 1,2,3 puts 3 on top. Reverse order puts 1 on top. extend(reversed([1,2,3])) adds 3,2,1 so 1 on top. Insert at index 0 in order ends with [3,2,1], 1 on top.

3. Final Answer:

   Use a loop to append elements in order: 1, then 2, then 3 -> Option A

4. Quick Check:

   Push in order to get last element on top [OK]

Hint: Push elements in order to have last on top [OK]

Common Mistakes:

• Pushing in reverse order causing wrong top
• Using insert(0, val) which adds at bottom
• Using extend(reversed([1, 2, 3])) which puts wrong order on top