struct list list next struct checker list ptr size_t idx bool check_lo

struct list
{
	list* next;
}

struct checker
{
    list* ptr;
	size_t   idx;
}

bool check_loop(list *lst)
{
	checker first = {lst, 0};
	while(first.ptr->next)
	{
		first.ptr = first.ptr->next;
		++first.idx;
		
		checker control = {lst, 0}
		while(control.ptr != first.ptr}
		{
			++control.idx;
			first.ptr = first.ptr->next;
		}
		if(control.idx < first.idx)
			return true;
	}
	return false;
}