Recording your solutions:

If you want to write down your soltuions, click on the Labels button. You can record each move as a two-letter pair: the piece label followed by a U, D, L or R for the direction. So the first two moves of the Donkey solution would be: BU FU (piece B up, piece F up). You can record multiple moves of the same piece similarly, e.g. GU GR, even though this "counts" as only one move.

Don't hesitate to give me your comments.


The Century Puzzle was created by one of the authors of reference (1). The original had piece C centered, so that the solution was 100 moves (actually 99 1/2).

The Donkey and Dad's Puzzler date back at least 100 years.

The Imp and The Devil's Nightcap were created by Robert L. Henderson.

Pandemonium was produced by the Pentangle Company in the 1970's and was based on earlier puzzles.

Special thanks to Robert L. Henderson for confirming and finding the shortest solutions.


(1) Berlekamp, E.R., Conway, J.H., and Guy, R.K., Winning Ways for your mathematical plays, Vol. 2: Games in particular, Academic Press, 1982.

(2) Hordern, L.E., Sliding Piece Puzzles, Oxford Univ. Press, 1986.


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