Stack Using Linked List vs Array Stack Trade-offs in DSA C - Compare & Choose

Challenge - 5 Problems

🧠 Conceptual

intermediate

Memory Usage Comparison Between Linked List Stack and Array Stack

Which statement correctly describes the memory usage difference between a stack implemented using a linked list and one using a fixed-size array?

A Both linked list and array stacks use fixed memory sizes determined at compile time.

B Array stack uses memory dynamically and can grow as needed, while linked list stack uses a fixed amount of memory regardless of usage.

C Linked list stack uses memory dynamically and can grow as needed, while array stack uses a fixed amount of memory regardless of usage.

D Linked list stack always uses less memory than array stack because it stores only data without pointers.

💡 Hint

Think about how each structure allocates memory when elements are added.

A linked list stack allocates memory for each new element dynamically, so it can grow or shrink as needed. An array stack allocates a fixed block of memory upfront, which may be larger than needed or limit growth.

❓ Predict Output

intermediate

Output of Push Operations on Array Stack

What is the printed state of the stack after pushing elements 10, 20, and 30 onto an array-based stack of size 5?

DSA C

int stack[5];
int top = -1;

void push(int x) {
    if (top < 4) {
        top++;
        stack[top] = x;
    }
}

void printStack() {
    for (int i = top; i >= 0; i--) {
        printf("%d -> ", stack[i]);
    }
    printf("null\n");
}

int main() {
    push(10);
    push(20);
    push(30);
    printStack();
    return 0;
}

A 10 -> 20 -> 30 -> null

B 30 -> 20 -> 10 -> null

C null

D 30 -> 10 -> 20 -> null

💡 Hint

Remember that the last pushed element is on top of the stack.

The stack follows Last-In-First-Out (LIFO). The last pushed element (30) is printed first, then 20, then 10.

❓ Predict Output

advanced

Output of Push and Pop Operations on Linked List Stack

What is the printed state of the stack after pushing 5, 15, then popping one element, then pushing 25 on a linked list stack?

DSA C

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

Node* top = NULL;

void push(int x) {
    Node* newNode = (Node*)malloc(sizeof(Node));
    newNode->data = x;
    newNode->next = top;
    top = newNode;
}

void pop() {
    if (top != NULL) {
        Node* temp = top;
        top = top->next;
        free(temp);
    }
}

void printStack() {
    Node* temp = top;
    while (temp != NULL) {
        printf("%d -> ", temp->data);
        temp = temp->next;
    }
    printf("null\n");
}

int main() {
    push(5);
    push(15);
    pop();
    push(25);
    printStack();
    return 0;
}

A 5 -> null

B 5 -> 25 -> null

C 15 -> 5 -> null

D 25 -> 5 -> null

💡 Hint

Pop removes the top element before pushing 25.

Push 5: stack is 5 -> null.
Push 15: stack is 15 -> 5 -> null.
Pop removes 15, stack is 5 -> null.
Push 25: stack is 25 -> 5 -> null.

🧠 Conceptual

advanced

Time Complexity Trade-offs Between Linked List and Array Stack

Which statement correctly compares the time complexity of push and pop operations in linked list stack and array stack implementations?

A Both linked list and array stacks have O(1) time complexity for push and pop operations.

B Linked list stack has O(n) push and pop, while array stack has O(1) for both.

C Array stack has O(n) push and pop due to shifting elements, linked list stack has O(1).

D Both linked list and array stacks have O(n) time complexity for push and pop operations.

💡 Hint

Consider how push and pop affect the top element in both implementations.

Both implementations add or remove elements only at the top, so push and pop are constant time operations (O(1)) in both cases.

🧠 Conceptual

expert

Choosing Between Linked List and Array Stack for Real-Time Systems

In a real-time system where predictable timing is critical, which stack implementation is generally preferred and why?

A Array stack is preferred because it provides fixed memory allocation and predictable access times.

B Linked list stack is preferred because dynamic memory allocation is faster and more predictable.

C Array stack is preferred because it allows unlimited growth without resizing.

D Linked list stack is preferred because it uses less memory and avoids fragmentation.

💡 Hint

Think about memory allocation and timing predictability in real-time systems.

Real-time systems require predictable timing and memory usage. Array stacks allocate fixed memory upfront, avoiding unpredictable delays from dynamic memory allocation used in linked lists.