delete_circular_linked_list.cpp

#include<iostream>
using namespace std;

class Node{
public:

int data;
Node *next;
}*head;

void create(int a[],int n){
int i;
Node *t,*last;
head = new Node();
head->data=a[0];
head->next=head;
last=head;

for(i=1;i<n;i++){

t = new Node();
t->data = a[i];


t->next = last->next;


last->next=t;


last=t;


}


}




void display(Node *h){


do{


cout<<h->data;


h = h->next;


}


while(h!=head);


cout<<"\n";


}




int Length(Node *p){


int len=0;


do{


len++;


p=p->next;


}


while(p!=head);


return len;


}




void insert(Node *p,int index,int x){


Node *t;


int i;


if(index<0 || index>Length(p))


return;


if(index==0){


t = new Node();


t->data=x;


if(head==NULL){


head=t;


head->next=head;


}


else{


while(p->next != head)p=p->next;


p->next=t;


t->next=head;


head=t;


}


}


else{


for(i=0;i<index-1;i++)p=p->next;


t=new Node();


t->data=x;


t->next=p->next;


p->next=t;


}


}




void rec_display(Node *h){


static int flag=0;


if(h!=head || flag==0){


flag=1;


cout<<h->data<<" ";


rec_display(h->next);


}


flag=0;


}

int Delete(Node *p,int index){
	Node *q;
	int i,x;
	
	if(index<0 || index>Length(head))
		return -1;
	
	if(index==1){
		while(p->next != head)p=p->next;
		x=head->data;
		if(head==p){
			delete head;
			head=NULL;
			
		}
		else{
			p->next = head->next;
			delete head;
			head = p->next;
			
		}
		
	}
	
	else{
		for(i=0;i<2;i++)
			p=p->next;
		q=p->next; 
		p->next=q->next;
		x=q->data;
		delete q;
		
	}
	return x;
	
}

int main(){
int a[] = {4,8,18,28,31};
create(a,5);
insert(head,5,10);
Delete(head,1);
rec_display(head);
return 0;


}