#include <iostream>

struct Node
{
    int value;
    Node* next;
};

class List
{
public:

    List() = default;

    ~List()
    {
        Node* current { head };
        while (current != nullptr)
        {
            Node* tmp { current };
            current = current->next;
            delete tmp;
        }
    }
    
    void insert(int value)
    {
        head = new Node { value, head };
        ++size;
    }

    void print() const
    {
        Node* tmp { head };
        while (tmp != nullptr)
        {
            std::cout << tmp->value << " ";
            tmp = tmp->next;
        }
        std::cout << std::endl;
    }

    List zipmerge(List const& other) const
    {
        List result { };
        
        if (size != other.size)
            return result;

        Node* left { head };
        Node* right { other.head };

        result.head = new Node { left->value, nullptr };
        left = left->next;

        Node* current { result.head };
        for (unsigned i { 1 }; i < size; ++i)
        {
            current->next = new Node { right->value, nullptr };
            current = current->next;

            current->next = new Node { left->value, nullptr };
            current = current->next;

            left = left->next;
            right = right->next;
        }

        current->next = new Node { right->value, nullptr };
        return result;
    }

private:

    Node* head { nullptr };
    unsigned size { };

};

int main()
{
    List l1 {};
    l1.insert(7);
    l1.insert(5);
    l1.insert(3);
    l1.insert(1);

    List l2 {};
    l2.insert(8);
    l2.insert(6);
    l2.insert(4);
    l2.insert(2);

    List l3 { l1.zipmerge(l2) };

    l1.print();
    l2.print();
    l3.print();
}