/************
3. A Doubly Linked List is a data structure consisting of nodes that have a pointer to the next 
object in the list as well as a pointer to the previous object.

class A{
public:
   .......... //Data
   A* next;
   A* previous;
   .....
}


Write a program to create a doubly linked list of nodes that hold an int and a char values as 
data. Include functions to print the list backward and forward, as well as to add items to the 
list and remove from the list.

**************/
#include<iostream>
using namespace std;

class A{
public:
  int a;
  char c;
  A* next;
  A* previous;
  A(){next=NULL;previous=NULL;}
  A(int i=0, char x='a'){
    a=i;
    c=x;
    next=NULL;
    previous=NULL;
  }

  void add_to_tail(A* p){
    A* temp=this;
    if(next==NULL){
      next=p;
      p->previous=temp;
    }
    else{
      while((temp->next)!=NULL){
	temp=temp->next;
      }
      p->previous=temp;
      temp->next=p;
      
    }
  }

 A* add_to_head(A* p){
   p->next=this;
   previous=p;
   return p;
 }


  void display(){
    A* p=this;
    while(p!= NULL){
      cout<<p->a<<"-->\t"<<p->c<<endl;
      p=p->next;
    }
  }
};

int main(){
  A a1(2,'a'),a2(4,'A'),a3(6,'C'),a4(8,'J'),a5(5,'k');
  A* head=&a1;
  head->display();
  cout<<"****adding to tail****"<<endl;
  head->add_to_tail(&a2);
  head->display();
  cout<<"****adding to tail****"<<endl;
  head->add_to_tail(&a4);
  head->display();
  cout<<"****adding to tail****"<<endl;
  head->add_to_tail(&a5);
  head->display();
  cout<<"****adding to head****"<<endl;
  head=head->add_to_head(&a3);
  head->display();

}