Pop Using Linked List Node in DSA Python - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to remove the first node from the linked list.

DSA Python

def pop_head(head):
    if head is None:
        return None
    new_head = head.[1]
    return new_head

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

Aprev

Bnext

Cvalue

Ddata

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'prev' instead of 'next' to get the new head.

Trying to access 'value' or 'data' instead of the next node.

To remove the first node, we return the next node as the new head.

2fill in blank

medium

Complete the code to pop the last node from a singly linked list.

DSA Python

def pop_tail(head):
    if head is None or head.next is None:
        return None
    current = head
    while current.[1].next is not None:
        current = current.next
    current.next = None
    return head

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

Aprev

Bdata

Cvalue

Dnext

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'prev' which does not exist in singly linked list nodes.

Trying to access 'value' or 'data' instead of the next node.

We traverse using the 'next' pointer to find the second last node.

3fill in blank

hard

Fix the error in the code to pop the head node and return its value.

DSA Python

def pop_head_value(head):
    if head is None:
        return None, None
    value = head.[1]
    head = head.next
    return value, head

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

Avalue

Bnext

Cdata

Dprev

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'value' which is not defined in the node.

Using 'next' or 'prev' which are pointers, not data.

The node's data is stored in the 'data' attribute, not 'value'.

4fill in blank

hard

Fill both blanks to pop the last node and return the updated list and popped value.

DSA Python

def pop_tail_value(head):
    if head is None:
        return None, None
    if head.next is None:
        return None, head.data
    current = head
    while current.[1].next is not None:
        current = current.next
    value = current.[2].data
    current.next = None
    return head, value

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

Anext

Bprev

Ddata

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'prev' which does not exist in singly linked lists.

Trying to access 'data' directly from current instead of current.next.

We use 'next' to traverse and access the last node's 'data'.

5fill in blank

hard

Fill all three blanks to pop the head node, return its value, and the updated list.

DSA Python

def pop_head_return(head):
    if head is None:
        return None, None
    value = head.[1]
    new_head = head.[2]
    head.[3] = None
    return value, new_head

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

Adata

Bnext

Dprev

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'prev' which is not present in singly linked list nodes.

Not disconnecting the old head's next pointer.

We get the data, update the head to next, and disconnect the old head's next.