Delete Node at End in DSA Python - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to move to the last node in a singly linked list.

DSA Python

while current.next [1] None:
    current = current.next

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

A==

B!=

C<

D>

Attempts:

3 left

💡 Hint

Common Mistakes

Using '==' instead of '!=' causes the loop to stop immediately.

Using '<' or '>' is invalid for None comparison.

The loop continues while current.next is not None, meaning current is not the last node.

2fill in blank

medium

Complete the code to update the second last node's next pointer to None, deleting the last node.

DSA Python

prev.next [1] None

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

A->

B==

C=

D!=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '==' instead of '=' causes a comparison, not assignment.

Using '!=' or '->' are syntax errors here.

We assign None to prev.next to remove the last node from the list.

3fill in blank

hard

Fix the error in the loop condition to find the second last node.

DSA Python

while current.next.next [1] None:
    current = current.next

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

A!=

B>

C<

D==

Attempts:

3 left

💡 Hint

Common Mistakes

Using '==' causes the loop to stop too early.

Using '<' or '>' is invalid for None comparison.

The loop continues while current.next.next is not None, so current stops at second last node.

4fill in blank

hard

Fill both blanks to correctly handle deleting the last node when list has only one node.

DSA Python

if head.next [1] None:
    head [2] None

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

A==

B!=

C=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '!=' in the if condition causes wrong logic.

Using '==' instead of '=' for assignment causes errors.

If head.next is None, it means only one node exists, so set head to None to delete it.

5fill in blank

hard

Fill all three blanks to complete the function that deletes the last node of a singly linked list.

DSA Python

def delete_last_node(head):
    if head is None:
        return None
    if head.next [1] None:
        return [2]
    current = head
    while current.next.next [3] None:
        current = current.next
    current.next = None
    return head

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

A==

Bhead

C!=

DNone

Attempts:

3 left

💡 Hint

Common Mistakes

Using '!=' instead of '==' in the if condition causes wrong logic.

Returning head instead of None for single node case.

Using '==' instead of '!=' in the loop condition causes the loop to stop too early.

If head.next == None, list has one node, so return None after deleting it. Loop while current.next.next != None to reach second last node.