Delete from End of Doubly Linked List in DSA Python - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to check if the doubly linked list is empty before deletion.

DSA Python

if self.head is [1]:
    return None

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

ANone

BFalse

CTrue

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Using True or False instead of None.

Checking if head equals 0.

We check if head is None to know if the list is empty.

2fill in blank

medium

Complete the code to move to the last node in the doubly linked list.

DSA Python

current = self.head
while current.[1] is not None:
    current = current.next

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

Atail

Bhead

Cprev

Dnext

Attempts:

3 left

💡 Hint

Common Mistakes

Using prev instead of next to move forward.

Using head or tail which are not node attributes.

We use current.next to move forward through the list until the last node.

3fill in blank

hard

Fix the error in updating the previous node's next pointer when deleting the last node.

DSA Python

if current.prev is not None:
    current.prev.[1] = None

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

Ahead

Bnext

Cprev

Dtail

Attempts:

3 left

💡 Hint

Common Mistakes

Setting prev instead of next.

Trying to set head or tail which are not node attributes.

We set the previous node's next pointer to None to remove the last node.

4fill in blank

hard

Fill both blanks to handle the case when the list has only one node during deletion.

DSA Python

if current.prev is [1] and current.next is [2]:
    self.head = None

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

ANone

BTrue

CFalse

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Using True or False instead of None.

Using 0 which is not a pointer.

If both prev and next are None, the list has one node, so head becomes None after deletion.

5fill in blank

hard

Fill all three blanks to complete the delete from end method in the doubly linked list.

DSA Python

def delete_from_end(self):
    if self.head is [1]:
        return None
    current = self.head
    while current.[2] is not None:
        current = current.next
    if current.prev is not [3]:
        current.prev.next = None
    else:
        self.head = None

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

ANone

BTrue

Cnext

DFalse

Attempts:

3 left

💡 Hint

Common Mistakes

Using True or False instead of None.

Mixing up prev and next pointers.

We check if head is None, move using next, and check if prev is None to update pointers correctly.