DLL.cpp

#include<bits/stdc++.h>
using namespace std;

class Node{

public:
    int data;
    Node* next;
    Node* prev;

    Node(int val){
        data=val;
        next=prev=NULL;
    }
};

class DoublyList{
    Node* head;
    Node* tail;


    public:
      DoublyList(){
        head=tail=NULL;
      }

      void push_front(int val){
         Node* newNode=new Node(val);

         if(head==NULL){
            head=tail=newNode;
         }else{
            newNode->next=head;
            head->prev=newNode;
            head=newNode;
         }
      }

      void push_back(int val){
        Node* newNode=new Node(val);

        if(head==NULL){
            head=tail=newNode;
        }else{
            newNode->prev=tail;
            tail->next=newNode;
            tail=newNode;
        }

      }

      void pop_front(){
        if(head==NULL){
            cout<<"DLL is empty\n";
            return;
        }

        Node* temp=head;
        head=head->next;

        if(head!=NULL){
            head->prev=NULL;
        }
        temp->next=NULL;
        delete temp;

      }

      void pop_back(){
          if(head==NULL){
            cout<<"DLL is empty\n";
            return;
        }
        Node* temp=tail;
        tail=tail->prev;

        if(tail!=NULL){
            tail->next=NULL;
        }
        temp->prev=NULL;
        delete temp;
      }

      void print(){
        Node* temp=head;
        while(temp!=NULL){
            cout<<temp->data<<"<=>";
            temp=temp->next;
        }
        cout<<"NULL\n";
      }

};

int main(){
    DoublyList dll;

    dll.push_front(1);
    dll.push_front(2);
    dll.push_front(3);
    dll.push_back(90);
    dll.push_back(87);
    dll.pop_front();
    dll.pop_back();


    dll.print();
    return 0;
}