#include<iostream.h>
#include<conio.h>
#include<stdlib.h>
void
insert_element(void);
int
Delete(void);
void
display(void);
struct node
{
int data;
struct node
*link;
}*f=NULL,*r=NULL;
void main()
{
               int choice,x;
               clrscr();
               cout<<"-----QUEUE
---"<<endl;
               cout<<"press 1. insert
the element at the ending"<<endl;
               cout<<"press 2. delete
the element from the ending"<<endl;
               cout<<"press 3.
display queue"<<endl;
               cout<<"press 4.
EXIT"<<endl;
               while(1)
               {
                               cout<<"enter
your choice:-";
                               cin>>choice;
                               switch(choice)
                               {
               case 1:
                               insert_element();
                               break;
               case 2:
                               x=Delete();
                               if(x!=-1)
                               cout<<"
deleted number is="<<x<<endl;
                               else
                               cout<<"
list is empty";
                               break;
               case 3:
                               cout<<"
QUEUE IS"<<endl;
                               display();
                               break;
               case 4:
                               exit(0);
                               break;
               default:
                               cout<<"plz
enter correct choice";
                               break;
               }//end of switch case
               getch();
               }//end of while
               }//end of main
               void insert_element()
               {
               char ch;
               do
               {
                               struct node
*temp;
                               temp=new node;
                               cout<<"enter
data:-";    //insert a node at the
end in the
                                                                                                                                                                                                           //  circular
queue
                               cin>>temp->data;
                               if(r==NULL
&& f==NULL)
                               {
                                              temp->link=temp;
                                              r=temp;
                                              f=temp;
                               }
                               else
                               {
                                              temp->link=f;
                                              r->link=temp;
                                              r=temp;
                               }
                               cout<<"do
you want to insert more node(y/n):-";
                               cin>>ch;
                      }while(ch=='y');
               }//end of function
               int Delete()
               {
                               struct node
*temp;
                               int x;
                               if(f==NULL
&& r==NULL)
                               {
                               return(-1);
                               }
                               else if(f==r)
                               {
                               x=r->data;       
                               temp=r;
                               f=NULL;
                               r=NULL;
                               delete(temp);
                               return(x);
                               }
                               else
                               {
                               struct node
*ptr1,*ptr2;
                               ptr1=f;
                               ptr2=f->link;
                               while(ptr2->link!=f)
                               {
                               ptr1=ptr2;
                               ptr2=ptr2->link;
                               }
                               x=ptr2->data;
                               temp=ptr2;
                               ptr1->link=f;
                               r=ptr1;
                               delete(temp);
                               return(x);
                               }
               }//end of function
               void display()
               {
                     struct node  *ptr;
                     ptr=f;                          //display a queue
                     while(ptr->link!=f)
                     {
                     cout<<"
"<<ptr->data;
                     ptr=ptr->link;
                     }
                     cout<<"
"<<ptr->data;
                     cout<<endl;
                }//end of function
 
 
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