Data Structure and Algorithm

/*******************************************************
 APPLICATION : Queue Implementation of Linked List
 CODED BY    : Ankit Pokhrel
 COMPILED ON : Borland C++ Ver 5.02
 DATE     : 2010 - June - 29
********************************************************/

#include "iostream.h"
#include "conio.h"
#include "process.h"

struct Queue //Structure to represent Queue
{
 int data;
 struct Queue *next,*front,*rear,*head; //Pointers to next node,head,front and rear
};

typedef struct Queue node; //Now, node represent Structure Queue

node *New; //Global Variable to represent node

void initialize(node *n)
{
 n -> next = n -> head = n -> front = n -> rear = NULL;
}

void create(node *n)
{
 New = new node; //Create a new node
 New -> data = NULL; //Initialize data
 New -> next = NULL; //Initialize next pointer field
 if(n -> head == NULL) //if first node
  n -> head = New; //Initialize head
}

void QINSERT(node *n,int ITEM)
{
 node *temp = n -> head;
 create(n); //Create a Node
 New -> data = ITEM; //Insert Item
 if(n -> front == NULL && n -> rear == NULL) //If first node
  n -> front = n -> rear = New; //front = rear = 1

 else
  {
   while(temp -> next != n -> rear -> next) //move to last node
   temp = temp -> next;

   temp -> next = New; //Last node points to new node
   n -> rear = New; //Now, rear is New node
  }
}

node* QDELETE(node *n)
{
 if(n -> head == NULL) //If the Queue is Empty
  {
    cout << "\nQueue Underflow";
    exit(0); //Exit from Program
   }

 node *deleted = n -> front;
 if(n -> front == n -> rear) //If only one element
  {
   n -> head = NULL;
  n -> front = n -> rear = NULL;
  }

 else
  n -> front = n -> front -> next; // Move to next node

 return deleted; //Return Deleted Node
}

void display(node *n)
{
 if(n -> head == NULL) //if no items
  {
    cout << "Queue is Empty";
    return;
   }

 node *temp = n -> front;
 cout << temp -> data << ' '; //Print First Item
 while(temp -> next != NULL)
  {
    temp = temp -> next; //Move to next node
    cout << temp -> data << ' '; //Print Next Item
   }
}

int main()
{
 int i,count = 5;
 node *list1 = new node,*list2 = new node,*list3 = new node;
 //Initialize all lists to avoid errors
 initialize(list1);
 initialize(list2);
 initialize(list3);
 cout << "Elements of First Queue : ";
 for(i = 1;i <= count;i++)
  QINSERT(list1,5*i); //Push 5 elements on Queue
 display(list1); //Display Elements of First List

 cout << "\n\nElements of Second Queue : ";
 for(i = 1;i <= count;i++)
  QINSERT(list2,7*i); //Push 5 elements on Queue
 display(list2); //Display Elements of Second List

 QINSERT(list3,(QDELETE(list1) -> data + QDELETE(list2) -> data)); //Add Elements of First Node and save to Third List
 i = 1; //Starts from 1 because first node is already processed
 while(i < count)
 {
  QINSERT(list3,(QDELETE(list1) -> data + QDELETE(list2) -> data)); //Add Elements
  i++;
 }

 cout << "\n\nElements of Third Queue (After Addition) : ";
 display(list3);

 getch();
 return 0;
}