Question

I'd like to make this portion of my project a recursive function... how can I accomplish this? This is what I have now. Thank you!!

// A wrapper to a recursive method that inverts the contents of the list
// @post the contents of the list are inverted such that
// the item previously at position 1 is at position item_count_,
// the item previously at position 2 is at position item_count_-1 ...
// the item previously at position ⌊item_count/2⌋ is at position
template<class T>
void LinkedList<T>::invert() {
    // Initialize current, previous and next pointers
    Node<T>* current = head_ptr_;
    Node<T>* prev = nullptr, *next_ = nullptr;


    while (current != nullptr)
    {
        // SAVE NEXT
        next_ = current->next_;

        // Flip the current NODE's POINTER
        current->next_ = prev;

        // Move POINTER one position ahead, by PUSHING IT ONE UP = NEXT
        prev = current;
        current = next_;
    }
    head_ptr_ = prev;
}

Answer 1

// this method takes a starting node, and reverse the 
// list starting from that.
// the result is the head of the resutant list.
// end is passed as reference, which gets filled in the 
// code.
template<class T>
Node<T>* LinkedList<T>::reverse(Node<T>* start, Node<T>* &end) {
        // if this is the only node in the list
        if(start == nullptr || start->next_ == nullptr) {
                end = start; // assign the node as end of list too.
                return start;
        }
        
        Node<T> *current = start;
        
        // reverse 
        Node<T> *result = reverse(start->next_, end);
        current->next_ = nullptr;
        end-next_ = current;
        return result;
}

template<class T>
void LinkedList<T>::invert() {
        Node<T>* end;
        
        // call recursive method.
        head_ptr_ = reverse(head_ptr_, end);
}

Please upvote, as i have given the exact answer as asked in question. Still in case of any concerns in code, let me know in comments. Thanks!