Delete Node at Specific Position in DSA Python - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to delete the head node of a singly linked list.

DSA Python

def delete_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'

A.data

B.prev

C.next

D.head

Attempts:

3 left

💡 Hint

Common Mistakes

Using .prev which is for doubly linked lists.

Trying to access .data instead of moving the head pointer.

To delete the head node, we return the next node as the new head.

2fill in blank

medium

Complete the code to delete the node at position 2 (0-based index) in a singly linked list.

DSA Python

def delete_at_pos(head, pos):
    if pos == 0:
        return head.next
    current = head
    for _ in range(pos - 1):
        current = current[1]
    current.next = current.next.next
    return head

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

A.prev

B.next

C.data

D.head

Attempts:

3 left

💡 Hint

Common Mistakes

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

Trying to access .data instead of moving the pointer.

To reach the node before the one to delete, we move using the .next attribute.

3fill in blank

hard

Fix the error in the code to delete a node at a given position in a singly linked list.

DSA Python

def delete_node(head, pos):
    if pos == 0:
        return head.next
    current = head
    for i in range(pos - 1):
        if current is None or current.next is None:
            return head
        current = current[1]
    current.next = current.next.next
    return head

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

A.next

B.head

C.data

D.prev

Attempts:

3 left

💡 Hint

Common Mistakes

Using .prev which is not defined in singly linked lists.

Trying to access .data instead of moving the pointer.

The pointer should move to the next node using .next to traverse the list correctly.

4fill in blank

hard

Fill both blanks to delete the node at position pos in a singly linked list safely.

DSA Python

def delete_node_safe(head, pos):
    if pos == 0:
        return head[1]
    current = head
    for _ in range(pos - 1):
        if current is None or current.next is None:
            return head
        current = current[2]
    current.next = current.next.next
    return head

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

A.next

B.prev

C.data

D.head

Attempts:

3 left

💡 Hint

Common Mistakes

Using .prev which is not available in singly linked lists.

Trying to access .data instead of moving the pointer.

Both blanks require moving to the next node using .next to traverse and update the list correctly.

5fill in blank

hard

Fill all three blanks to delete the node at position pos with boundary checks in a singly linked list.

DSA Python

def delete_node_full(head, pos):
    if pos == 0:
        return head[1]
    current = head
    for _ in range(pos - 1):
        if current is None or current.next is None:
            return head
        current = current[2]
    if current.next is None:
        return head
    current.next = current.next[3]
    return head

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

A.next

B.prev

D.data

Attempts:

3 left

💡 Hint

Common Mistakes

Using .prev which is not defined in singly linked lists.

Trying to access .data instead of moving the pointer.

All blanks require the .next attribute to move through and update the linked list correctly.