\begin{frame}
    \frametitle{\problemtitle}
  \begin{block}{Problem}
    Given a tree, find a minimal subset of nodes, such that every node has distance less than $k$ to this subset.
    \end{block}
    \begin{itemize}
        \item<+-> Solve the problem greedily. Consider a node with maximum depth $u$.
        \item<+-> Walk up $k-1$ steps to the node $v$ and add $v$ to the subset.
        \item<+-> Remove the subtree rooted at $v$ and repeat all the steps.
    \end{itemize}
\end{frame}