StacksUsingLinkedList.cpp

/*******
 Following Node class and main already created internally. You can directly use that.
 
#include<iostream>
using namespace std;


template <typename T>
class Node {
    public :
    T data;
    Node<T> *next;
    
    Node(T data) {
        this -> data = data;
        next = NULL;
    }
};

#include "Stack.h"
    int main() {
        
        Stack<int> st;
        
        int choice;
        cin >> choice;
        int input;
        
        while (choice !=-1) {
            if(choice == 1) {
                cin >> input;
                st.push(input);
            }
            else if(choice == 2) {
                int ans = st.pop();
                if(ans != 0) {
                    cout << ans << endl;
                }
                else {
                    cout << "-1" << endl;
                }
            }
            else if(choice == 3) {
                int ans = st.top();
                if(ans != 0) {
                    cout << ans << endl;
                }
                else {
                    cout << "-1" << endl;
                }
            }
            else if(choice == 4) {
                cout << st.getSize() << endl;
            }
            else if(choice == 5) {
                cout << st.isEmpty() << endl;
            }
            cin >> choice;
        }
    
    } 
***********/

template <typename T>
class Stack {
    Node<T> *head;
    int size;		// number of elements prsent in stack
    
    public :
    
    Stack() {
        head=NULL ; 
        size=0 ; 
    }
    
    int getSize() {
        return size ; 
    }
    
    bool isEmpty() {
     return size==0 ;    
    }
    
    void push(T element) {
        Node<T> *newnode = new Node<T>(element); 
        newnode->next=head ; 
        head=newnode ; 
        size++ ; 
    }
    
    T pop() {
        // Return 0 if stack is empty. Don't display any other message
        if(isEmpty()){
            return 0 ; 
        }else{
        T ans = head->data ; 
        Node<T> *temp=head ; 
        head=head->next ; 
        delete temp ; 
        size-- ; 
        return ans ; 
        }
    }
    
    T top() {
        // Return 0 if stack is empty. Don't display any other message
        
        if(isEmpty()){
            return 0 ; 
        }else{
            return head->data ; 
        }
        
    }
    
  
    
};