First task from the first DSP exam 2019/2020 (81786)

zad1.cpp

void fillgaps(node<int>* l) {
    if(l == nullptr) {
        return;
    }

    node<int>* current = l;
	while (current->next != NULL)
	{
		if (current->data != (current->next->data - 1))
		{
            node<int>* neww = new node<int>();
            neww->data = current->data + 1;
            neww->next = current->next;
            current->next = neww;
		}
		current = current->next;
	}
}