  A Level Ancestory query LA($u$, $d$) asks for the the ancestor of the node
$u$ at a depth $d$. We present a simple solution, which pre-processes the tree
in $O(n)$ time with $O(n)$ extra space, and answers the queries in $O(\log\
{n})$ time. Though other optimal algorithms exist, this is a simple enough
solution that could be taught and implemented easily.
