circular link list

#include<bits/stdc++.h>
using namespace std;

class Node{
public:
    int data;
    Node *next;
};

class LinkList{
    Node *last = NULL;
public:
    void add_to_first(int value){
        if(last != NULL)
            return;

        last = new Node();
        last->data = value;
        last->next = last;
    }

    void add_begin(int x){
        if(last == NULL)
        {
            return add_to_first(x);
        }

        Node *newNode = new Node();
        newNode->data = x;
        newNode->next = last->next;
        last->next = newNode;
    }

    void add_end(int x){
        if(last == NULL)
        {
            return add_to_first(x);
        }

        Node *newNode = new Node();
        newNode->data = x;
        newNode->next = last->next;
        last->next = newNode;
        last = newNode;
    }

    void add_after(int x,int value)
    {
        if(last == NULL)
        {
            cout<<"Link list is empty";
            return ;
        }

        Node *newNode,*head;
        head = last->next;

        do{
            if(head->data == value)
            {
                newNode = new Node();
                newNode->data = x;
                newNode->next = head->next;
                head->next = newNode;
                if(head == last)
                    last = newNode;
                return ;
            }
            head = head->next;
        }while(head != last->next);

        cout<<value<<" not present in the list."<<endl;

    }

    void delete_Node(int key)
    {
        if(last == NULL)
            return ;
        //Node *curr = last-next, *prev;
        Node *curr , *prev;
        curr = last->next;
        while(curr->data != key)
        {
            if(curr->next == last->next)
            {
                cout<<"Given node id not found"<<endl;
                //break;
                return ;
            }
            prev = curr;
            curr = curr->next;
        }

        if(curr->next == last->next)
        {
            last = NULL;
            delete(curr);
            return ;
        }
        if( curr == last->next)
        {
            prev = last->next;
//            while( prev->next != last->next)
//            {
//                prev = prev->next;
//            }
            last->next = curr->next;
            prev->next = last->next;
            delete(curr);
        }
        else if( curr->next == last->next)
        {
            prev->next = last->next;
            delete(curr);
        }
        else
        {
            prev->next = curr->next;
            delete(curr);
        }
    }

    void display(){
        Node *temp;

        if(last == NULL){
            cout<<"Link List is Empty."<<endl;
            return ;
        }
        temp = last->next;
        do{

            cout<< temp->data<<" ";
            temp = temp->next;
        }while(temp != last->next);
    }

};

int main(){
    LinkList ll;
    ll.add_to_first(20);
    ll.add_begin(10);
    ll.add_end(30);
    ll.add_after(500,20);
    ll.delete_Node(500);
    ll.display();
}