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

Practice - 5 Tasks

1fill in blank

easy

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

DSA C

if (head == [1]) {
    printf("List is empty\n");
    return;
}

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

A0

BNULL

Chead

Dtail

Attempts:

3 left

💡 Hint

Common Mistakes

Checking if head == 0 instead of NULL

Checking tail instead of head

Using an uninitialized pointer

We check if head is NULL to determine if the list is empty.

2fill in blank

medium

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

DSA C

struct Node* temp = head;
while (temp->[1] != NULL) {
    temp = temp->next;
}

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

Anext

Bprev

Cdata

Dhead

Attempts:

3 left

💡 Hint

Common Mistakes

Using prev instead of next to traverse forward

Checking data instead of next pointer

Using head inside the loop incorrectly

We use the next pointer to move forward to the last node.

3fill in blank

hard

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

DSA C

if (temp->prev != NULL) {
    temp->prev->[1] = NULL;
} else {
    head = NULL;
}

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

Aprev

Bhead

Cdata

Dnext

Attempts:

3 left

💡 Hint

Common Mistakes

Setting prev pointer to NULL instead of next

Setting head pointer inside the if block incorrectly

Not handling the case when temp->prev is NULL

We set the previous node's next pointer to NULL to mark it as the new end.

4fill in blank

hard

Fill both blanks to correctly free the last node and update the list.

DSA C

struct Node* toDelete = temp;
temp = temp->prev;
free([1]);
temp->[2] = NULL;

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

AtoDelete

Btemp

Cprev

Dnext

Attempts:

3 left

💡 Hint

Common Mistakes

Freeing temp instead of toDelete

Setting prev pointer to NULL instead of next

Not updating pointers after free

We free the node stored in toDelete and set temp's next pointer to NULL.

5fill in blank

hard

Fill all three blanks to handle deletion when only one node exists.

DSA C

if (head->[1] == NULL) {
    free(head);
    head = [2];
    tail = [3];
}

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

Anext

BNULL

Chead

Dprev

Attempts:

3 left

💡 Hint

Common Mistakes

Checking prev instead of next

Setting head or tail to head instead of NULL

Not freeing the node before resetting pointers

If the only node's next is NULL, free it and set head and tail to NULL.