View source for Talk:N-queens problem

== Tcl: All Solutions ==
Is the goal to find one solution, or all solutions? --[[Special:Contributions/164.67.235.98|164.67.235.98]] 19:59, 12 September 2009 (UTC)

: I've put up code to find all solutions; finding just one is a trivial adaptation of that (stop iterating after the first solution is found...) —[[User:Dkf|Donal Fellows]] 20:37, 12 September 2009 (UTC)

:: I read the task's requirements differently. &nbsp; It said to &nbsp; <big> ''Solve the eight queens puzzle'', </big> &nbsp; and once solved, stopped looking for more solutions. &nbsp; I didn't see any point in providing multiple answers. &nbsp; Of the &nbsp; '''92''' &nbsp; solutions on an &nbsp; '''8x8''' &nbsp; board, &nbsp; '''12''' &nbsp; are fundamental solutions --- and just sifting (choosing which ones to display) those out (I thought) isn't part of the task's requirement. &nbsp; ··· And if the answers are an ASCII art depiction of the chessboard, the amount of output would be greatly compounded. &nbsp; -- [[User:Gerard Schildberger|Gerard Schildberger]] ([[User talk:Gerard Schildberger|talk]]) 21:57, 6 May 2016 (UTC)

== Python permission ==
I thought I might copy the email trail where I got permission to post a Python solution from its original author:

<small><pre>Subject:
Re: 8-Queens
From:
Steve Howell <showell30@YY.com>
Date:
Mon, 14 Sep 2009 23:07:09 -0700 (PDT)
To:
Paddy McCarthy <paddy3118@XX.net>

Thanks!

--- On Mon, 9/14/09, Paddy McCarthy <paddy3118@XX.net> wrote:


    From: Paddy McCarthy <paddy3118@XX.net>
    Subject: Re: 8-Queens
    To: "Steve Howell" <showell30@YY.com>
    Date: Monday, September 14, 2009, 11:54 AM

    Ta very much. It's in place.

    Steve Howell wrote:
>     Please do, thank you.
>
>     Sent from my iPhone
>
>     On Sep 13, 2009, at 10:43 AM, Paddy McCarthy <paddy3118@XX.net> wrote:
>
>>     Hi,
>>     I wondered if you would allow me to submit your 8-Queens solution to  Rosetta  Code ?
>>
>>
>>     -- Donald 'Paddy' McCarthy
>>     http://paddy3118.blogspot.com/</pre></small>
--[[User:Paddy3118|Paddy3118]] 04:28, 6 September 2010 (UTC)

== Removing existing C code: webbug? ==

I added a C solution, then realized the existing C example is sending results to some http server.  This amounts to a web bug, I'm removing it, until the intent of the webbug can be clarified and justified --[[User:Ledrug|Ledrug]] 03:34, 6 July 2011 (UTC)

:Apparently the ip address is somewhere in germany, on a machine owned by 23media.eu.  Also, a google search finds http://forum.chip.de/c-net/c-code-socket-laeuft-1443464.html which suggests that this is a machine that at one point was owned by Leonie Schöller.  Then again, http://178.77.72.203/wbb2/thread.php?postid=3648536 suggests a machine owned by someone named Manuela. --[[User:Rdm|Rdm]] 04:44, 6 July 2011 (UTC)
:: Whoever it was, that was a fairly odd thing to do: it's not like code here gets compiled and run very often--  &mdash;[[User:Ledrug|Ledrug]] 05:25, 6 July 2011 (UTC)

== REXX mistake == 
I'm not familiar with REXX, nor do I have any idea how to fix it; however, the two outputs produced (for board sizes 8 and 20) are both unsuccessful attempts at nqueens. In the 8x8 board, rows 4 and 6 (1-up) have queens in diagonal contradiction; in the 20x20 board, (at least, didn't bother to check more) rows 1 and 6 have queens in diagonal contradiction. 

Anyone familiar enough to know whether this is a printing error or a solving error, and either way, how to fix it?

: It was my mistake, I had cut and pasted the solutions from an earlier version, corrected the REXX program, but neglected to updated the outputs. &nbsp; I re-ran the REXX program and pasted the chessboard to the OUTPUT sections. -- [[User:Gerard Schildberger|Gerard Schildberger]] ([[User talk:Gerard Schildberger|talk]]) 16:39, 22 July 2013 (UTC)

== What about profiling? == 
When doing the Erlang version I thought it would be much faster to calculate diagonals in advance. It did not help at all. I should have profiled before changing the code.

Is there a task on Rosettacode that looks at profiling? Similar to [[Time_a_function]], but for several functions in a task. [[User:bengt]] Sat Dec  7 13:23:33 CET 2013

== Pari/GP ==

I am not known for my compact code, but I have a script in Pari/GP.  Not optimized to any extent.  Just contact me.--[[User:Billymacc|Billymacc]] ([[User talk:Billymacc|talk]]) 12:42, 14 October 2017 (UTC)