Why Circular Linked List and Real World Use Cases in DSA C - Test Your Knowledge

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a circular linked list node that points to itself.

DSA C

struct Node {
    int data;
    struct Node* next;
};

struct Node* createNode(int value) {
    struct Node* newNode = (struct Node*)malloc(sizeof(struct Node));
    newNode->data = value;
    newNode->next = [1];
    return newNode;
}

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

AnewNode

BNULL

C0

D&newNode

Attempts:

3 left

💡 Hint

Common Mistakes

Setting next to NULL instead of pointing to the node itself.

Using the address of the pointer variable instead of the node.

In a circular linked list, the node's next pointer points to itself when it is the only node, so newNode->next = newNode; creates a circular link.

2fill in blank

medium

Complete the code to traverse a circular linked list starting from head and print all node data once.

DSA C

void printList(struct Node* head) {
    struct Node* temp = head;
    if (head == NULL) return;
    do {
        printf("%d -> ", temp->data);
        temp = [1];
    } while (temp != head);
    printf("NULL\n");
}

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Ahead

Btemp

Chead->next

Dtemp->next

Attempts:

3 left

💡 Hint

Common Mistakes

Using head instead of temp->next, causing an infinite loop.

Not updating temp at all.

To move through the circular linked list, we update temp to temp->next in each iteration.

3fill in blank

hard

Fix the error in the code to insert a new node after the head in a circular linked list.

DSA C

void insertAfterHead(struct Node* head, int value) {
    struct Node* newNode = (struct Node*)malloc(sizeof(struct Node));
    newNode->data = value;
    newNode->next = head->next;
    head->next = [1];
}

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Ahead

BNULL

CnewNode

Dhead->next

Attempts:

3 left

💡 Hint

Common Mistakes

Assigning head->next to head instead of newNode.

Assigning NULL to head->next.

To insert the new node after head, set head->next = newNode; so the head points to the new node.

4fill in blank

hard

Fill both blanks to check if a circular linked list is empty or has only one node.

DSA C

int isSingleNode(struct Node* head) {
    if (head == NULL) return 0;
    if (head->next == [1] || head->next == [2]) return 1;
    return 0;
}

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Ahead

BNULL

Chead->next

Dhead->data

Attempts:

3 left

💡 Hint

Common Mistakes

Checking head->next against NULL instead of head.

Using wrong pointers for comparison.

For a circular linked list, if head->next == head (only one node), we return 1. The check for NULL is not typical in circular lists as next should never be NULL.

5fill in blank

hard

Fill all three blanks to create a function that counts nodes in a circular linked list.

DSA C

int countNodes(struct Node* head) {
    if (head == NULL) return 0;
    int count = 1;
    struct Node* temp = head->[1];
    while (temp != [2]) {
        count++;
        temp = temp->[3];
    }
    return count;
}

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

Anext

Bhead

Ddata

Attempts:

3 left

💡 Hint

Common Mistakes

Using data instead of next to move to the next node.

Comparing temp to NULL instead of head.

Start from the node after head (head->next), loop until back to head, moving to temp->next each time, counting nodes.