Stack Implementation Using Linked List in DSA C - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a new node for the stack.

DSA C

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

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

A0

BNULL

Cnode

Ddata

Attempts:

3 left

💡 Hint

Common Mistakes

Assigning NULL or 0 instead of the input data.

Assigning the node pointer itself.

The new node's data field should be set to the input parameter 'data'.

2fill in blank

medium

Complete the code to check if the stack is empty.

DSA C

int isEmpty(struct Node* top) {
    return [1] == NULL;
}

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

Atop->next

Btop

Ctop->data

DNULL

Attempts:

3 left

💡 Hint

Common Mistakes

Checking top->next instead of top.

Comparing data field to NULL.

The stack is empty if the top pointer is NULL.

3fill in blank

hard

Fix the error in the push function to correctly add a new node on top of the stack.

DSA C

void push(struct Node** top_ref, int data) {
    struct Node* node = newNode(data);
    node->next = [1];
    *top_ref = node;
}

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

A*top_ref->next

Btop_ref

C*top_ref

Dtop_ref->next

Attempts:

3 left

💡 Hint

Common Mistakes

Using top_ref instead of *top_ref.

Using top_ref->next which is invalid pointer access.

The new node's next should point to the current top node, which is *top_ref.

4fill in blank

hard

Fill both blanks to correctly pop the top element from the stack and return its data.

DSA C

int pop(struct Node** top_ref) {
    if (isEmpty(*top_ref))
        return -1;
    struct Node* temp = [1];
    int popped = temp->data;
    *top_ref = [2];
    free(temp);
    return popped;
}

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

A*top_ref

B(*top_ref)->next

Ctop_ref

D(*top_ref)

Attempts:

3 left

💡 Hint

Common Mistakes

Assigning temp to top_ref instead of *top_ref.

Not updating *top_ref to the next node.

temp should point to the current top node (*top_ref), and top_ref should be updated to the next node (*top_ref)->next.

5fill in blank

hard

Fill in the blank to implement a peek function that returns the top element's data without removing it.

DSA C

int peek(struct Node* top) {
    if (top == NULL)
        return -1;
    return [1];
}

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

Atop->data

Btop->next

Ctop

DNULL

Attempts:

3 left

💡 Hint

Common Mistakes

Returning top pointer instead of its data.

Returning top->next which is the next node, not the data.

The peek function returns the data of the top node without modifying the stack.