void decode_huff(node * root, string s) {
    string result;
    node* ptr = root;
    for (int i = 0; i < s.size(); ++i) {
        switch (s[i]) {
            case '0': ptr = ptr->left; break;
            case '1': ptr = ptr->right; break;
        }
        if (!ptr->left && !ptr->right) {
            result += ptr->data;
            ptr = root;
        }
    }
    cout << result << endl;
}