Implementing a Stack Using a Queue

In this article, we will learn how to implement a stack data structure using a single queue.

Problem Statement: Implement a stack using a single queue with the following operations:

• Push: Add an element to the top of the stack.

• Pop: Remove the top element from the stack.

• Top: Get the top element of the stack without removing it.

• isEmpty: Check if the stack is empty.

Example:

// Creating a stack

Stack s;

// Push elements to the stack

s.push(10);

s.push(20);

s.push(30);

// Get the top element

s.top(); // Output: 30

// Pop the top element

s.pop(); // Output: 30

// Check if the stack is empty

s.isEmpty(); // Output: false

Solution:

To solve this problem, we will follow these steps:

Steps to Implement:

1.    Define the Stack Class:

o   Create a class Stack with a queue and a variable for the size of the stack.

2.    Implement Push Operation:

o   Add the element to the queue.

o   Rotate the queue elements such that the newly added element becomes the front element of the queue.

3.    Implement Pop Operation:

o   Check if the stack is empty. If not, remove the front element from the queue.

4.    Implement Top Operation:

o   Return the front element of the queue.

5.    Implement isEmpty Operation:

o   Check if the queue is empty.