Deep Dark Fantasy

vector<int> DeepDarkFantasy(Node* init = nullptr) {
        vector<int> a;
        if (init == nullptr) init = this->root;
        stack<Node*> s;
        s.push(init);
        while (!s.empty()) {
            Node* that = s.top();
            if (that->left != nullptr) {
                s.push(that->left);
                continue;
            }
            else if (that->right != nullptr) {
                s.pop();
                if (s.size() > 0) {
                    Node* temp = s.top();
                    temp->left = nullptr;
                }
                s.push(that->right);
                a.push_back(that->data);
            }
            else {
                s.pop();
                if (s.size() > 0) {
                    Node* temp = s.top();
                    temp->left = nullptr;
                }
                a.push_back(that->data);
            }
        }
        return a;
    }