Delete by Value in Doubly Linked List in DSA Python - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

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

DSA Python

if self.head is [1]:
    return

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

ATrue

B0

CFalse

DNone

Attempts:

3 left

💡 Hint

Common Mistakes

Using 0 or False instead of None

Checking the wrong attribute

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

2fill in blank

medium

Complete the code to move to the next node in the list during traversal.

DSA Python

current = current.[1]

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

Aprev

Bnext

Ctail

Dhead

Attempts:

3 left

💡 Hint

Common Mistakes

Using prev instead of next

Using head or tail which are not node pointers

To traverse forward, we move to the next node.

3fill in blank

hard

Fix the error in updating the previous node's next pointer after deletion.

DSA Python

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

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

Anext

Bprev

Chead

Dtail

Attempts:

3 left

💡 Hint

Common Mistakes

Assigning to prev instead of next

Assigning to head or tail incorrectly

We update the next pointer of the previous node to skip the deleted node.

4fill in blank

hard

Fill both blanks to correctly update the next node's previous pointer and handle tail update.

DSA Python

if current.next is not None:
    current.next.[1] = current.prev
else:
    self.[2] = current.prev

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

Aprev

Bnext

Chead

Dtail

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping prev and next in assignments

Updating head instead of tail when next is None

The next node's prev pointer should skip the deleted node. If there is no next node, update the tail.

5fill in blank

hard

Fill all three blanks to complete the delete by value method in a doubly linked list.

DSA Python

def delete_by_value(self, value):
    current = self.head
    while current is not None:
        if current.data == [1]:
            if current.prev is not None:
                current.prev.[2] = current.next
            else:
                self.head = current.next
            if current.next is not None:
                current.next.[3] = current.prev
            else:
                self.tail = current.prev
            return
        current = current.next

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

Avalue

Bnext

Cprev

Ddata

Attempts:

3 left

💡 Hint

Common Mistakes

Comparing with wrong variable

Swapping next and prev in pointer updates

We compare current.data with value. Then update pointers: previous node's next and next node's prev.