vector<int> rightSideView(TreeNode* root) {
    vector<int> result;
    if (!root) return result;

    queue<TreeNode*> q;
    q.push(root);

    while (!q.empty()) {
        int sz = q.size();

        for (int i = 0; i < sz; ++i) {
            TreeNode* node = q.front();
            q.pop();

            __________________________

            if (node->left) q.push(node->left);
            if (node->right) q.push(node->right);
        }
    }

    return result;
}