Inflight magazine puzzle

*To*: mathgroup at smc.vnet.net*Subject*: [mg50393] Inflight magazine puzzle*From*: Paul Abbott <paul at physics.uwa.edu.au>*Date*: Wed, 1 Sep 2004 01:49:43 -0400 (EDT)*Organization*: The University of Western Australia*Sender*: owner-wri-mathgroup at wolfram.com

The following puzzle appeared in an AirCanada inflight magazine. It's not too hard to solve by hand, but I'd be interested to hear about clever solutions using Mathematica. What would be particularly nice would be to see an animation showing the steps (and possible back-tracking) towards the unique solution. I'd like to include the best solution(s) in an issue of The Mathematica Journal. Cheers, Paul ________________________________________________________________________ In the diagram below (copy the Cell[...] below and paste into a Notebook, answering yes when it asks you if you want Mathematica to interpret it), place the numbers 1 through 9 so that each row, column, and 3 x 3 subsquare (separated by thick black lines) contains each number exactly once. Cell[BoxData[FormBox[RowBox[{RowBox[{"puzzle", "=", GridBox[{ {" ", "3", " ", "9", " ", " ", " ", "8", " "}, {" ", " ", "6", "2", " ", "3", "7", "9", " "}, {" ", " ", " ", "1", " ", " ", " ", " ", " "}, {" ", "2", " ", "3", " ", " ", " ", "7", " "}, {" ", " ", " ", " ", "7", " ", " ", "6", "4"}, {"1", " ", " ", " ", " ", " ", " ", " ", " "}, {" ", "5", " ", " ", " ", "4", "9", " ", " "}, {" ", "7", "2", " ", " ", " ", " ", " ", " "}, {" ", "9", " ", " ", "5", " ", "8", "3", " "}}]}], ";"}], StandardForm]], "Input", GridBoxOptions->{ GridFrame->True, RowLines->{0.25, 0.25, True, 0.25, 0.25, True, 0.25}, ColumnLines->{0.25, 0.25, True, 0.25, 0.25, True, 0.25} } ] -- Paul Abbott Phone: +61 8 9380 2734 School of Physics, M013 Fax: +61 8 9380 1014 The University of Western Australia (CRICOS Provider No 00126G) 35 Stirling Highway Crawley WA 6009 mailto:paul at physics.uwa.edu.au AUSTRALIA http://physics.uwa.edu.au/~paul

**Follow-Ups**:**Re: Inflight magazine puzzle***From:*Andrzej Kozlowski <akoz@mimuw.edu.pl>

**Re: Inflight magazine puzzle***From:*DrBob <drbob@bigfoot.com>