  Given a graph $G=(V,E)$ and a positive integer $t\geq2$, the task in the
vertex cover $P_t$ ($VCP_t$) problem is to find a minimum subset of vertices
$F\subseteq V$ such that every path of order $t$ in $G$ contains at least one
vertex from $F$. The $VCP_t$ problem is NP-complete for any integer $t\geq2$
and has many applications in real world. Recently, the authors presented a
dynamic programming algorithm running in time $4^p\cdot n^{O(1)}$ for the
$VCP_3$ problem on $n$-vertex graphs with treewidth $p$. In this paper, we
propose an improvement of it and improved the time-complexity to $3^p\cdot
n^{O(1)}$.
  The connected vertex cover $P_3$ ($CVCP_3$) problem is the connected
variation of the $VCP_3$ problem where $G[F]$ is required to be connected.
Using the Cut\&Count technique, we give a randomized algorithm with runtime
$4^p\cdot n^{O(1)}$ for the $CVCP_3$ problem on $n$-vertex graphs with
treewidth $p$.
