## Plank puzzle span diagram

This is a span diagram for the Route-66 plank puzzle, courtesy
of Graham's solver (one of the key stages of solving a plank
puzzle is to work out all valid placements for all planks, referred
to as plank *spans*). Note there are a total of 54 (hexadecimal
36) distinct spans in this puzzle, yet the solution is 66 moves
(so you just know you are going to have to walk some of those
spans several times!). Infact Route-66 is the only puzzle so
far where the number of moves actually exceeds the number of
plank spans.

fig.1: span diagram for Route-66