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From: "Vladimir Olensky" <vladimir_olensky@yahoo.com>
Subject: Re: Eight Queens problem (was Re: Kindness)
Date: 1999/09/06
Message-ID: <rt872lon8os47@corp.supernews.com>#1/1
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 <1999Sep3.125818.1@eisner> <37D02CC0.BEF1BC69@mitre.org>
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Date: 1999-09-06T00:00:00+00:00
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Daryle Walker wrote in message ...
>In article <37D02CC0.BEF1BC69@mitre.org>, "Robert I. Eachus"
><eachus@mitre.org> wrote:
>
>
>What is this Eight Queens Problem?  I've heard of it only in passing; I
>never had to do it as an assignment (BTW, I've been out of school for 2
>years).  I'm guessing it's how to place eight queen chess pieces on a
>chess board without any of them threatening another.  Where can I find
>more information about it?  What is Nico Lomuto's Ada-task solution?
>
>[For those who haven't heard of chess, a chess board has a grid of 64
>squares in a 8-by-8 square.  A queen piece can attack any enemy piece that
>can be directly intercepted via a row, column, or 45-degree diagonal.]
>
>[Just from a minimal description, I can guess a solution:
>   1. Put a queen on a random square
>   2. Mark the queen's square, squares on the same row and column,
>      and squares diagonally connected, invalid
>   3. Repeat the previous steps for the next 7 queens
>      (using valid squares only, of course)
> I got the feeling that there's some gotchas to this newbie approach,
> like all good CS problems have.]


Eight Queens Problem and  was discussed and illustrated
in "Programming in Modula-2" written by Niklaus Wirth.
There were several editions of this book. Third edition was
published by Springer-Verlag in 1985.
This book may be  useful not only for those using Modula-2  but
also for those  learning  Ada.

Regards.