The optimum solution to Fiendish can be found here.
Fiendish was devised by hand, over a period of several days. My sole aim was to improve on my previous best (Route-66) which I had stumbled on more by luck than judgement, and was a huge leap forward in its time. A nifty windows-based (C++) plank-puzzle editor/solver (by applet author - Graham Rogers) was used to verify the solution. Fiendish is actually shorter than Route-66, but more complex and compact, as (hopefully) illustrated in the following table. Note I (used to*) measure plank puzzle complexity by move-over-span ratio which is why I rank Fiendish above Route-66. Fiendish and Route-66 are the only puzzles to date (03/03/01*) with a move-over-span ratio greater than 1 (meaning the number of moves actually exceeds the number of possible plank positions).
|Grid||9x9 (square)||8x8 (square)|
|Planks||3 (1+2+3)||4 (1+2+3+4)|
|Shortest solution||66 moves||57 moves|
(*) In late March 2001 Pascal Wassong well and truely smashed my move-over-span ratio record with a plank-puzzle of his own invention entitled The Centrifugal Force. This puzzle requires an incredible 342 moves and has a move-over-span ratio of 4.62. Try it here.