h will be recorded in the distance map. Also you can
record the shortest paths tree in a predecessor map: for each vertex
<i>u in V</i>, <i>p[u]</i> will be the predecessor of <i>u</i> in
the shortest paths tree (unless <i>p[u] = u</i>, in which case <i>u</i> is
either the source or a vertex unreachable from the source).  In
addition to these two options, the user can provide their own
custom-made visitor that takes actions during any of the
algorithm's event points <a href="#4">[4]</a>.</P>

<P>
Dijkstra's