Traversal Forward and Backward in DSA C - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to move the pointer forward in a singly linked list.

DSA C

current = current[1];

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

A->next

B->prev

C.next

D.prev

Attempts:

3 left

💡 Hint

Common Mistakes

Using '.next' instead of '->next' in pointer access.

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

In a singly linked list, to move forward, you use the 'next' pointer with '->' operator.

2fill in blank

medium

Complete the code to move the pointer backward in a doubly linked list.

DSA C

current = current[1];

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

A->prev

B->next

C.prev

D.next

Attempts:

3 left

💡 Hint

Common Mistakes

Using '.prev' instead of '->prev' in pointer access.

Using 'next' pointer to move backward.

In a doubly linked list, to move backward, you use the 'prev' pointer with '->' operator.

3fill in blank

hard

Fix the error in the traversal code to move forward in a singly linked list.

DSA C

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

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

A->prev

B->next

C.next

D.prev

Attempts:

3 left

💡 Hint

Common Mistakes

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

Using '.' operator instead of '->' for pointer access.

To move forward in a singly linked list, use 'current = current->next;'.

4fill in blank

hard

Fill both blanks to traverse backward and print data in a doubly linked list.

DSA C

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

// To move backward:
current = tail;
while (current != NULL) {
    printf("%d -> ", current->data);
    current = current[2];
}
printf("NULL\n");

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

A->next

B->prev

C.prev

D.next

Attempts:

3 left

💡 Hint

Common Mistakes

Using '.' operator instead of '->'.

Mixing up next and prev pointers.

To move forward, use '->next'. To move backward, use '->prev' in doubly linked list.

5fill in blank

hard

Fill all three blanks to create a function that prints a doubly linked list forward and backward.

DSA C

void printList(struct Node* head, struct Node* tail) {
    struct Node* current = head;
    while (current != NULL) {
        printf("%d -> ", current[1]);
        current = current[2];
    }
    printf("NULL\n");

    current = tail;
    while (current != NULL) {
        printf("%d -> ", current[3]);
        current = current->prev;
    }
    printf("NULL\n");
}

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

A->data

B->next

D->prev

Attempts:

3 left

💡 Hint

Common Mistakes

Using '.' instead of '->' for pointer access.

Using wrong pointer to move forward or backward.

To print data, use '->data'. To move forward, use '->next'. The last print also uses '->data'.