Stack Implementation Using Linked List in DSA Python - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a stack data structure?

A stack is a collection where elements are added and removed in a last-in, first-out (LIFO) order. Think of a stack of plates where you add or remove the top plate only.

intermediate

What is the main advantage of using a linked list to implement a stack?

Using a linked list allows the stack to grow and shrink dynamically without a fixed size limit, unlike arrays which have a fixed size.

beginner

What does the 'push' operation do in a stack implemented with a linked list?

The 'push' operation adds a new element at the top of the stack by creating a new node and linking it as the new head of the list.

beginner

What happens during the 'pop' operation in a linked list stack?

The 'pop' operation removes the top element by unlinking the head node and returning its value, then updating the head to the next node.

beginner

Why is it important to check if the stack is empty before popping?

Because popping from an empty stack causes an error or undefined behavior. Checking prevents trying to remove from an empty list.

What order does a stack follow when adding and removing elements?

A Random Order

B First In, First Out (FIFO)

C Last In, First Out (LIFO)

D Sorted Order

A stack follows Last In, First Out (LIFO) order, meaning the last element added is the first one removed.

In a linked list stack, where is the new element added during a push?

A At the head (start) of the list

B At the tail (end) of the list

C In the middle of the list

D At a random position

New elements are added at the head of the linked list to represent the top of the stack.

What should you do before performing a pop operation on a stack?

A Clear the stack

B Check if the stack is empty

C Sort the stack

D Add a new element

Always check if the stack is empty to avoid errors when popping.

What is the time complexity of push and pop operations in a linked list stack?

A O(n^2)

B O(n)

C O(log n)

D O(1)

Both push and pop operations take constant time O(1) because they only involve the head node.

Which of the following is NOT a benefit of using a linked list for stack implementation?

A Faster random access

B Dynamic size

C No wasted space

D Easy insertion and deletion at head

Linked lists do not provide fast random access; accessing elements by index is slower compared to arrays.

Explain how push and pop operations work in a stack implemented using a linked list.

Think about adding and removing from the start of the linked list.

Describe the advantages of using a linked list over an array for implementing a stack.

Consider flexibility and memory usage differences.