Question

Assuming:
struct node
{
    int data;
    node * next;
    node * tail;
};

and 
copyList(node * head);

write a function to recursively copy a circular linked list.

Answer 1

HERE IS MY CODE :-

#include <iostream>

using namespace std;

struct node{

int data;
node* next;
node* tail;
};

node* add(node *head,int val)
{
if(head==NULL)
{
node* temp = new node();
temp->data = val;
temp->next = temp;
return temp;
}

node* ptr = head;

while(ptr->next!=head)
{
ptr = ptr->next;
}

node* temp = new node();
temp->data = val;
temp->next = head;
ptr->next = temp;

return head;

}

void print(node* head)
{
node* ptr = head;
if(ptr==NULL)
{
cout<<"\n";
return ;
}

do
{
cout<<ptr->data<<" ";
ptr = ptr->next;

}
while(ptr!=head);

cout<<endl;
return ;

}

node* recursiveCopy(node* head,node* start)
{
if(head->next==start)
{
node* temp = new node();
temp->data = head->data;
head->next = NULL;
return temp;
}

node* temp = new node();
temp->data = head->data;
temp->next = recursiveCopy(head->next,start);
}

node* copyList(node* head)
{
if(head!=NULL)
{
node* start = recursiveCopy(head,head);
node* ptr = start;
while(ptr->next!=NULL)
{
ptr = ptr->next;
}
ptr->next = start;
return start;
}

}

int main()
{

node* head = NULL;

head = add(head,5);
head = add(head,6);
head = add(head,6);
head = add(head,8);
head = add(head,6);

cout<<"Old List: ";
print(head);

node* newHead = copyList(head);

cout<<"New List: ";
print(newHead);

}

WHAT I HAVE DONE IS COPY A OLD LIST TO NEW LIST

OUTPUT IS :-

OLD LIST :- 5 6 6 8 9

NEW LIST :- 5 6 6 8 9