STACKSUsingLinkedLists.cpp

#include<iostream>
#include<stack>
using namespace std;

class Node{
    public:
    int data;
    Node* next;

    Node(int d){
        this->data = d;
        this->next = NULL;
    }
};

class Stack{
    Node* head;
    int capacity;
    int currSize;
    public:
    Stack(int c){
        this->capacity = c;
        this->currSize = 0;
        head = NULL;
    }

    bool isEmpty() {
        return this->head == NULL;
    }

    bool isFull(){
        return this->currSize == this->capacity;
    }
    void push(int data){
        if(this->currSize == this->capacity) {
            cout<<"Overflow\n";
            return;
        }
        Node* new_node = new Node(data);
        new_node->next = this->head;
        this->head = new_node;
        this->currSize++;
}

    int pop(){
        if(this->head == NULL){
            cout<<"Underflow\n";
            return INT_MIN;
        }
        Node* new_head = this->head->next;
        this->head->next = NULL;
        Node* tobeRemoved = this->head;
        int result = tobeRemoved->data;
        delete tobeRemoved;
        this->head = new_head;
        this->currSize--;
        return result;
    }

    int getTop(){
        if(this->head == NULL){
            cout<<"Underflow\n";
            return INT_MIN;
        }
        return this->head->data;
    }

    int size() {
        return this->currSize;
    }
};

int main() {
    Stack st(5);
    st.push(1);
    st.push(2);
    st.push(3);
    cout<<st.getTop()<<endl;
    st.push(4);
    st.push(5);
    cout<<st.getTop()<<"\n";
    st.push(6);

    cout<<st.pop()<<endl;
    cout<<st.pop()<<endl;

    // cout<<st.getTop()<<"\n";
    cout<<st.isEmpty()<<endl;
    cout<<st.isFull()<<endl;
    cout<<st.size()<<endl;
    return 0;
}




// int main() {
//     stack<int> st;
//     st.push(1);
//     st.push(2);
//     st.push(3);
//     cout<<st.top()<<endl;
//     st.push(4);
//     st.push(5);
//     cout<<st.top()<<"\n";
//     st.pop();
//     st.pop();
//     cout<<st.top()<<endl;
//     cout<<st.empty()<<endl;
//     cout<<st.size()<<endl;
//     return 0;
// }