Circular vs Linear Linked List Key Difference in DSA C - Interactive Comparison Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to check if a linked list is circular by comparing the next pointer of the last node.

DSA C

if (last->next == [1]) {
    printf("List is circular\n");
} else {
    printf("List is linear\n");
}

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

Atemp

BNULL

Clast

Dhead

Attempts:

3 left

💡 Hint

Common Mistakes

Checking if last->next is NULL instead of head.

Confusing the last node pointer with the head pointer.

In a circular linked list, the last node's next pointer points back to the head node.

2fill in blank

medium

Complete the code to traverse a circular linked list until it reaches the head again.

DSA C

struct Node* temp = head;
do {
    printf("%d -> ", temp->data);
    temp = temp->[1];
} while (temp != head);

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Anext

Bchild

Cparent

Dprev

Attempts:

3 left

💡 Hint

Common Mistakes

Using prev pointer which may not exist in singly linked lists.

Using incorrect pointer names.

To traverse a linked list, we move from one node to the next using the next pointer.

3fill in blank

hard

Fix the error in the code that tries to detect a linear linked list by checking if next pointer is NULL.

DSA C

while (temp != NULL) {
    printf("%d -> ", temp->data);
    temp = temp->[1];
}
printf("NULL\n");

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Ahead

Bprev

Cnext

Dtail

Attempts:

3 left

💡 Hint

Common Mistakes

Using prev pointer which may not exist.

Using head or tail pointers incorrectly.

To move through a linear linked list, we use the next pointer until it becomes NULL.

4fill in blank

hard

Fill both blanks to create a function that inserts a new node at the end of a circular linked list.

DSA C

void insertEnd(struct Node** head_ref, int data) {
    struct Node* new_node = (struct Node*)malloc(sizeof(struct Node));
    new_node->data = data;
    if (*head_ref == NULL) {
        new_node->next = new_node;
        *head_ref = new_node;
        return;
    }
    struct Node* temp = *head_ref;
    while (temp->[1] != *head_ref) {
        temp = temp->[2];
    }
    temp->next = new_node;
    new_node->next = *head_ref;
}

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Anext

Bprev

Chead

Ddata

Attempts:

3 left

💡 Hint

Common Mistakes

Using prev pointer which may not exist.

Using incorrect pointer names.

To find the last node in a circular linked list, we move using the next pointer until we reach the head again.

5fill in blank

hard

Fill all three blanks to create a function that deletes the head node of a circular linked list.

DSA C

void deleteHead(struct Node** head_ref) {
    if (*head_ref == NULL) return;
    if ((*head_ref)->next == *head_ref) {
        free(*head_ref);
        *head_ref = NULL;
        return;
    }
    struct Node* temp = *head_ref;
    while (temp->[1] != *head_ref) {
        temp = temp->[2];
    }
    struct Node* to_delete = *head_ref;
    temp->next = (*head_ref)->[3];
    *head_ref = (*head_ref)->next;
    free(to_delete);
}

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

Anext

Bprev

Dhead

Attempts:

3 left

💡 Hint

Common Mistakes

Using prev pointer which may not exist.

Not updating the last node's next pointer.

To delete the head in a circular linked list, find the last node using next pointers, then update its next to the second node.