IterativeTree

TreeNode<int>* MakeTree(int value, TreeNode<int>* parent, int depth, int max_depth) {
        auto new_node = new TreeNode<int>{value, parent, nullptr, nullptr};
        if (depth <= max_depth) {
            new_node->left = MakeTree(value - (1<<(max_depth - depth)), new_node, depth + 1, max_depth);
            new_node->right = MakeTree(value + (1<<(max_depth - depth)), new_node, depth + 1, max_depth);
        }
        return new_node;
    }

    void NextEffectiveness() {
        using namespace std;
        using T = TreeNode<int>;

        T* root = MakeTree(0, nullptr, 0, 20);
        cout << root << endl;

        T* iter = begin(root);

        while (iter) {
            cout << iter->value << " "s;
            iter = next(iter);
        }
        cout << endl;

        DeleteTree(root);
    }