This puzzle, although interesting, is commonly given to beginning
programming students.
Yes, but I posted here because of "XSLT 1.0 + exslt:node-set()" solution
and the two questions I have (Muenchian grouping / functional style).
I remember facing it myself. One I have never seen solved
are the number of boards where less than eight queens is the maximum.
Please be more precise on what you count as "a board".
Does the board contain less than 8 queens for your problem?
Or does the board always contain 8 queens, some threatening another?
In the latter case the answer is:
(64 choose 8) - 92 = 4426165368
Long ago I posted some queen-puzzles on a (German language) chess forum.
Here you can see a position with 5 queens threatening all fields:
http://www.schachmatt.de/69-schachraetsel/2764-3xdamen-uberdeckung.html#post22269
It is not possible to threaten all fields with only 4 queens.
So for the first problem the count of all positions with 5, 6 and 7 queens
threatening all fields seem to be what you are interested in, right?
Mit besten Gruessen / Best wishes,
Hermann Stamm-Wilbrandt
Level 3 support for XML Compiler team and Fixpack team lead
WebSphere DataPower SOA Appliances
https://www.ibm.com/developerworks/mydeveloperworks/blogs/HermannSW/
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From: "Mark" <mark(_at_)knihtisk(_dot_)org>
To: <xsl-list(_at_)lists(_dot_)mulberrytech(_dot_)com>,
Date: 04/21/2012 08:25 PM
Subject: Re: [xsl] n-queens?
This puzzle, although interesting, is commonly given to beginning
programming students. I remember facing it myself. One I have never seen
solved are the number of boards where less than eight queens is the
maximum.
Mark
-----Original Message-----
From: Ivan Shmakov
Sent: Saturday, April 21, 2012 8:26 AM
To: xsl-list(_at_)lists(_dot_)mulberrytech(_dot_)com
Cc: Ivan Shmakov
Subject: Re: [xsl] n-queens?
Michael Hopwood <michael(_at_)editeur(_dot_)org> writes:
I'm no chess OR maths expert but - surely they are not actually chess
queens if any two of the same colour can threaten each other? The
puzzle using actual chess queens, at least one of which is of the
other colour, would look quite different...
AIUI, for the purposes of this puzzle, /each/ of the queens is
assumed to be of its own distinct colour.
--cut: http://en.wikipedia.org/wiki/Eight_queens_puzzle --
The eight queens puzzle is the problem of placing eight chess queens
on an 8×8 chessboard so that no two queens attack each other. Thus,
a solution requires that no two queens share the same row, column,
or diagonal. The eight queens puzzle is an example of the more
general n-queens problem of placing n queens on an n×n chessboard,
where solutions exist for all natural numbers n with the exception
of 2 and 3.
--cut: http://en.wikipedia.org/wiki/Eight_queens_puzzle --
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