Lecture 231:- Stack Operations using Linked List

Here's a C++ implementation of stack operations using a singly linked list:

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#include <iostream> class Node { public:    int data;    Node* next;    Node(int data) : data(data), next(nullptr) {} }; class Stack { private:    Node* top; public:    Stack() : top(nullptr) {}    ~Stack() {        while (!isEmpty()) {            pop();        }    }    bool isEmpty() {        return top == nullptr;    }    void push(int value) {        Node* newNode = new Node(value);        newNode->next = top;        top = newNode;    }    void pop() {        if (isEmpty()) {            std::cout << "Stack Underflow! Cannot pop element." << std::endl;            return;        }        Node* temp = top;        top = top->next;        delete temp;    }    int peek() {        if (isEmpty()) {            std::cout << "Stack is empty. Cannot peek." << std::endl;            return -1;        }        return top->data;    }    void display() {        Node* current = top;        while (current) {            std::cout << current->data << " ";            current = current->next;        }        std::cout << std::endl;    } }; int main() {    Stack stack;    stack.push(1);    stack.push(2);    stack.push(3);    std::cout << "Top element: " << stack.peek() << std::endl; // Output: 3    stack.pop();    stack.push(4);    std::cout << "Stack elements: ";    stack.display(); // Output: 4 2 1    stack.pop();    stack.pop();    stack.pop(); // Trying to pop more elements than present    std::cout << "Stack elements: ";    stack.display(); // Output: Stack is empty.    return 0; }

In this implementation, the Node class is used to represent each node in the singly linked list. The Stack class uses the top pointer to keep track of the top element of the stack.

The push method adds an element to the top of the stack by creating a new node and updating the top pointer. The pop method removes the top element from the stack, and the peek method returns the value of the top element without removing it.

The display method is added to display the elements of the stack from top to bottom.

In the main function, we demonstrate how to use the Stack class by creating a stack. We push elements onto the stack, peek at the top element, and then pop elements. We also display the elements of the stack at different stages. The output will show the elements being pushed, popped, and displayed.