circularll.cpp

/* This file was first created on 15th September,2018 by Keshav Tangri
This is for educational purposes only.
This is for B.Tech Students who are or will be studying Data Structures in there curriculum
For queries mail me @ : tangri57@gmail.com
*/
#include <iostream>
#include<stdlib.h>

using namespace std;
class Node{
public:
Node* next;
int data;
};

class cll{
public:
Node* head = new Node;
cll(){
head=NULL;
}
Node* createnode(int val);
void display();
void addeleatbeg(int val);
void addeleatlast(int val);
void deleleatbeg();
void deleleatlast();
void divideintotwo();
void exchangefirstandlastnode();
};


int main()
{
int value;
int i;
cll obj;
while(1){
 cout<<"\n\n1.ADD ELEMENT AT BEGINNING\n2.ADD ELEMENT AT THE LAST\n3.DISPLAY LIST\n4.DELETE AT BEG\n5.DELETE AT LAST\n6.DIVIDE IN TWO\n7.EXCHANGE FIRST AND LAST NODE\n8.EXIT\nChoose your Option : ";   
 cin>>i;
switch(i){
case 1:
cout<<"\n\nEnter value you want to add : ";
cin>>value;
obj.addeleatbeg(value);
break;
case 2:
cout<<"\n\nEnter value you want to add : ";
cin>>value;
obj.addeleatlast(value);
break;
case 3:
obj.display();
break;
case 4:
obj.deleleatbeg();
break;
case 5:
obj.deleleatlast();
break;
case 6:
obj.divideintotwo();
break;
case 7:
obj.exchangefirstandlastnode();
break;
case 8:
exit(0);
break;
}
}
return 0;
}
//createnode function
Node* cll::createnode(int val){
Node* temp = new Node;
temp->data = val;
return temp; 
}
//display function
void cll::display(){
if(head==NULL){
cout<<"\n\nBLANK LIST !\n\n";
return;
}else{
Node* ptr=new Node;
ptr = head;
do{
cout<<ptr->data<<" ";
ptr=ptr->next;
}while(ptr!=head);
}
}
//element at the beginning
void cll::addeleatbeg(int val){
Node* temp = createnode(val);
if(head==NULL){
head=temp;
temp->next = head;
cout<<"\n\nELEMENT ADDED !\n\n";
}else{
Node* ptr = new Node;
ptr = head;
while(ptr->next!=head){
ptr=ptr->next;
}
temp->next=head;
ptr->next = temp;
head = temp;

cout<<"\n\nELEMENT ADDED !\n\n";
}
}
//add element at last
void cll::addeleatlast(int val){
if(head==NULL){
addeleatbeg(val);
}else{
Node* temp = createnode(val);
Node* ptr = new Node;
ptr=head;
while(ptr->next!=head){
ptr=ptr->next;
}
ptr->next = temp;
temp->next = head;
cout<<"\n\nELEMENT ADDED !\n\n";
}
}
//delete element at beg
void cll::deleleatbeg(){
if(head==NULL){
cout<<"\n\nUNDERFLOW !\n\n";
return;
}else if(head->next==head){
head = NULL;
cout<<"\n\nELEMENT AT BEGINNING DELETED !\n\n";
return;
}
Node * ptr = new Node;
Node * preptr = new Node;
preptr=head;
do{
preptr=preptr->next;
}while(preptr->next!=head);
ptr=head;
head = ptr->next;
preptr->next = head;
delete ptr;
cout<<"\n\nELEMENT AT BEGINNING DELETED !\n\n";
}
//delete element at last
void cll::deleleatlast(){
if(head==NULL){
cout<<"\n\nUNDERFLOW !\n\n";
return;
}else if(head->next==head){
head = NULL;
cout<<"\n\nELEMENT AT LAST DELETED !\n\n";
return;
}
Node * preptr = new Node;
Node * ptr =new Node;
ptr=head;
do{
preptr =ptr;
ptr=ptr->next;
}while(ptr->next!=head);
preptr->next =head;
delete ptr;
cout<<"\n\nELEMENT AT LAST DELETED !\n\n";
}
//Divide list into 2 lists
void cll::divideintotwo(){
if(head==NULL){
cout<<"\n\nBLANK LIST!\n\n";
return;
}
Node* ptr = new Node;
ptr=head;
int coun = 1,h1,h2;
do{
coun++;
ptr=ptr->next;
}while(ptr->next!=head);
ptr=head;
if(coun%2==0){
h1=coun/2;
h2=h1;
}else{
h1 = coun/2+1;
h2 = coun/2;
}
cll ob1,ob2;
for(int i=1;i<=coun;i++){
if(i<=h1){
ob1.addeleatlast(ptr->data);
ptr=ptr->next;
}else{
ob2.addeleatlast(ptr->data);
ptr=ptr->next;
}
}
cout<<"\nFIRST HALF : ";
ob1.display();
cout<<"\n\n";
cout<<"\nSECOND HALF : ";
ob2.display();
cout<<"\n\n";
}
//exchange first and last node
void cll::exchangefirstandlastnode(){
if(head==NULL){
cout<<"\n\nBLANK LIST !\n\n";
return;
}
Node* prev=new Node;
Node* lastp = new Node;
Node* firstp = new Node;
firstp= head;
lastp=head;
while(lastp->next!=head){
prev=lastp;
lastp=lastp->next;
}
head = lastp;
lastp->next=firstp->next;
prev->next=firstp;
firstp->next = head;
cout<<"\n\nELEMENTS SWAPPED/EXCHANGED\n\n";
}