C++ program to implement the deque (double ended queue) ADT using a double linked list

Here is the C++ program to implement Double ended queue ADT using a double linked list..!

 

#include<iostream>
#include<conio.h>
#include<stdlib.h>
using namespace std;

class node
{
public:
int data;
class  node *next;
class node *prev;
};

class dqueue: public node
{
  node *head,*tail;
  int top1,top2;
  public:
   dqueue()
   {
   top1=0;
   top2=0;
   head=NULL;
   tail=NULL;
   }
  void push(int x){
    node *temp;
    int ch;
    if(top1+top2 >=5)
    {
      cout <<"dqueue overflow";
      return ;
    }
    if( top1+top2 == 0)
      {
        head = new node;
        head->data=x;
        head->next=NULL;
        head->prev=NULL;
        tail=head;
        top1++;
      }
     else
     {
       cout <<" Add element 1.FIRST 2.LAST\n enter ur choice:";
       cin >> ch;


       if(ch==1)
       {
         top1++;
         temp=new node;
         temp->data=x;
         temp->next=head; 
         temp->prev=NULL;
         head->prev=temp;
         head=temp;
       }
       else
       {
         top2++;
         temp=new node;
         temp->data=x;
         temp->next=NULL;
         temp->prev=tail;
         tail->next=temp;
         tail=temp;
       }

     }
  }
  void pop()
  {
   int ch;
   cout <<"Delete 1.First Node 2.Last Node\n Enter ur choice:";
   cin >>ch;
   if(top1 + top2 <=0)
   {
     cout <<"\nDqueue under flow";
     return;
   }
   if(ch==1)
   {
     head=head->next;
     head->prev=NULL;
     top1--;
   }
   else
   {
     top2--;
     tail=tail->prev;
     tail->next=NULL;
   }
  }



  void display()
  {
   int ch;
   node *temp;
   cout <<"display from 1.Staring 2.Ending\n Enter ur choice";
   cin >>ch;
   if(top1+top2 <=0)
   {
     cout <<"under flow";
     return ;
   }
   if (ch==1)
   {
    temp=head;
    while(temp!=NULL)
    {
      cout << temp->data <<" ";
      temp=temp->next;
    }
   }
   else
   {
    temp=tail;
    while( temp!=NULL) 
    {
      cout <<temp->data << " ";
      temp=temp->prev;
    }
   }
    }
  };

  main()
  {
    dqueue d1;
    int ch;
    while (1){
    cout <<"1.INSERT  2.DELETE  3.DISPLAU  4.EXIT\n Enter ur choice:";
    cin >>ch; 
    switch(ch)
    {
    case 1:     cout <<"enter element";
        cin >> ch;
        d1.push(ch); break;
    case 2: d1.pop(); break;
    case 3: d1.display(); break;
    case 4: exit(1);
    }
  }}

OUTPUT

1.INSERT 2.DELETE 3.DISPLAU 4.EXIT

Enter ur choice:1

enter element4

1.INSERT 2.DELETE 3.DISPLAU 4.EXIT

Enter ur choice:1

enter element5

Add element 1.FIRST 2.LAST

enter ur choice:1

1.INSERT 2.DELETE 3.DISPLAU 4.EXIT

Enter ur choice:1

enter element6

Add element 1.FIRST 2.LAST

enter ur choice:2

1.INSERT 2.DELETE 3.DISPLAU 4.EXIT

Enter ur choice:3

display from 1.Staring 2.Ending

Enter ur choice1

5 4 6 1.INSERT 2.DELETE 3.DISPLAU 4.EXIT

Enter ur choice:2

Delete 1.First Node 2.Last Node

Enter ur choice:1

1.INSERT 2.DELETE 3.DISPLAU 4.EXIT

Enter ur choice:3

display from 1.Staring 2.Ending

Enter ur choice1

4 6 1.INSERT 2.DELETE 3.DISPLAU 4.EXIT

Enter ur choice:4