sll

#include <bits/stdc++.h>

class ListNode
{
    int data;
    ListNode* next;
    public:
    ListNode(int d, ListNode* next)
    {
        this->data = d;
        this->next = next;
    }

    ListNode & get_next()
    {
        return *(this->next);
    }

    void setNext(ListNode n)
    {
        this->next = &n;
    }

    bool isLast()
    {
        return !(this->next);
    }
};

class SLL
{
    ListNode * root;
    public:
    SLL()
    {
        root = nullptr;
    }

    void add_back(ListNode n)
    {
        if(root == nullptr) root = &n;
        else{
            ListNode * p = root;
            while(p->isLast())
            {
                p = &(p->get_next());
            }
        }
    }
};


int main()
{
    SLL l(5, nullptr);
    ListNode el(4, nullptr);
    l.setNext(el);
    return 0;
}