Stack Using Linked List vs Array Stack Trade-offs in DSA C - Interactive Comparison Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to push an element onto an array-based stack.

DSA C

void push(int stack[], int *top, int value, int max_size) {
    if (*top < max_size - 1) {
        stack[++(*top)] = [1];
    }
}

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

Avalue

Btop

Cmax_size

Dstack

Attempts:

3 left

💡 Hint

Common Mistakes

Using the wrong variable instead of the value to push.

Not incrementing the top index before assignment.

The value to push onto the stack is assigned to the next position in the array.

2fill in blank

medium

Complete the code to create a new node for a linked list stack push operation.

DSA C

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

Node* push(Node* top, int value) {
    Node* new_node = (Node*)malloc(sizeof(Node));
    if (new_node == NULL) return top;
    new_node->data = [1];
    new_node->next = top;
    return new_node;
}

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

Avalue

Btop

CNULL

Dnew_node

Attempts:

3 left

💡 Hint

Common Mistakes

Assigning the pointer top instead of the value.

Forgetting to assign the data field.

The new node's data field should be set to the value being pushed onto the stack.

3fill in blank

hard

Fix the error in the array stack pop function to return the popped value correctly.

DSA C

int pop(int stack[], int *top) {
    if (*top == -1) {
        return -1; // Stack empty
    }
    return stack[[1]];
}

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

A*top

B(*top)++

C--(*top)

D(*top)--

Attempts:

3 left

💡 Hint

Common Mistakes

Not decrementing top (e.g., using just `*top`).

Using pre-decrement `--(*top)` which accesses the wrong element.

Use the post-decrement operator to return the value at the current top and then decrement the top index.

4fill in blank

hard

Fill both blanks to check if the linked list stack is empty and return the top element's data.

DSA C

int peek(Node* top) {
    if (top == [1]) {
        return -1; // Stack empty
    }
    return top->[2];
}

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

ANULL

B0

Cdata

Dnext

Attempts:

3 left

💡 Hint

Common Mistakes

Checking top against 0 instead of NULL.

Returning the next pointer instead of data.

Check if top is NULL to see if stack is empty, then return the data field of the top node.

5fill in blank

hard

Fill all three blanks to implement a function that returns the current size of an array stack.

DSA C

int size(int *top) {
    return [1] + [2];
}

// Usage example:
// int current_size = size(&[3]);

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

A*top

B1

Ctop

Dstack

Attempts:

3 left

💡 Hint

Common Mistakes

Returning top without adding 1.

Passing the wrong variable to the function.

The size is *top + 1 because top starts at -1 when empty. Pass &top where top is the top index variable.