Four on a Match

Kadon has many fun puzzles and some contests.

by solving one of them, I received Four on a Match two years ago:

I think it was good time to publish it :P

Combinatorial Explosion

I think the discussion should have more emphasis in the best practice of using this kind of tool; Just like it is mentioned and used in the MatrixGame & TheLuckyString problems, we need to generate certain rules/filters to optimize the search. To look for all n! possibilities probably never will be a feasible solution. This is also called Combinatorial Explosion which verbatim refers to a growth almost impossible to sustain for the time of this type of TC problems.

So more important than the implementation ( which is assumed know -next_permutation()- that this is called Algorithm L in Knuth's TAOCP 4: 7.2.1.2) it is the good use some criteria for pruning combinations (permutations) and at the end we obtain a reasonable running time.

Many problems use this kind of booby-trap to let the programmer to try to solve with a plenty quick solution which runs over all permutations (or combinations) that finish with a timeout or an unnecessary overhead as resources used (such us memory).

The 25 Holes Challenge

Uno de los contests aun abiertos en Kadon es el basado en su juego Vee-21.

Mi solucion es:

Kadon Contests

Ademas de tener varios productos de muy buena calidad e ingenio ;)
Kadon tiene unos pequennos concursos, interesantes como desafio mental, a ver si se animan:

http://www.gamepuzzles.com/contests.htm

Oracle Certified Expert, Java EE 6 Web Component Developer

Despues de pasar el ex-SCWCD y ahora OCPWCD es el momento de ver lo nuevo de EE 6 y sobre todo acerca de Servlet 3.0: OCEJWCD

Lo interesante de este examen es que requiere un porcentaje mas bajo para poder pasarlo: 64%

http://education.oracle.com/pls/web_prod-plq-dad/db_pages.getpage?page_id=458&get_params=p_track_id:JEE6WCD

WLS 12c: Distinctive Recipes: Repository of Solutions

A wonderful book with a collection of straightforward information and solutions. Interesting recipes, direct to provide clear solutions and examples.

It explains several topics -traversal to middleware tier including last Cloud technology- that are not 100% covered in the official Oracle documentation.

It gives suggestions of different tools to work with WLS 12c one popular, but another hidden open source gems, such us, NeatBeans, j4psh, Grinder, BadBoy, JMeter, Jolokia, among others.

Supported by webcasts and useful samples for EJB Timer, JSP stress test case, Web Services, that can be downloaded from author's site.

At the end, a great easy to use all-in-one cookbook to save hours of researching in different resources.

Grandes Números

A medida que la civilizacion avanza se usa numeros mayores, por diferentes motivos.
Uno de ellos es lamentablemente la inflación de ciertos paises por

Un caso historico es Alemania justo antes de la Segunda Guerra Mundial y hoy en dia es Zimbawe:

https://en.wikipedia.org/wiki/File:Zimbabwe_Hyperinflation_2008_notes.jpg

http://gamasutra.com/view/feature/183525/the_burning_of_star_wars_the_old_.php

Oracle VirtualBox stuck installation

When re-installing Virtualbox, it hangs and nothing happens.

Googling I found the solution:
http://www.tomshardware.com/forum/38226-63-problems-oracle-virtualbox

Pasting the answers here:

VirtualBox doesn't install startup items or services on Windows host, rather it installs several device drivers which may be the ones giving you problems. Depending on your settings during the installation, these drivers should be in your system:  

VBoxDrv VirtualBox Support Driver Oracle Corporation c:\windows\system32\drivers\vboxdrv.sys  

VBoxNetAdp VirtualBox Host-Only Network Adapter Driver Oracle Corporation 

c:\windows\system32\drivers\vboxnetadp.sys VBoxNetFlt VirtualBox 

Bridged Networking Driver Oracle Corporation 

c:\windows\system32\drivers\vboxnetflt.sys  

VBoxUSBMon VirtualBox USB Monitor Driver Oracle Corporation c:\windows\system32\drivers\vboxusbmon.sys 

TAP-Win32 Adapter V9 - VirtualBox Bridged Networking Driver Miniport  

Try using a program like Autoruns to disable those drivers and check the Device Manager for any VirtualBox related entries that may be marked as a problem. If the failed installation still shows on in your Programs and Features, try using CCleaner to remove that entry from the list. Before trying to reinstall again, download the latest release of VirtualBox and make sure the installer's checksum is correct. 
Post a reply if this helps you or not. 

--------

Thanks for those pointers - I think I have now solved the problem!  

Starting with a system that has VirtualBox installed and was thus hanging on reboot I did several 'shutdown->restart's to prove the frequency. I got 4 hangs out of 8 reboots.  

Then I looked for the drivers. I could only find 3 - VboxNetAdp, VboxUsbMon and VboxDrv. (The last 2 are 'hidden - non PnP drivers' you have to enable hidded drivers to see them. I disabled all three and repeated the restart tests: 8/8 success!  

Now I changed the status of VboxDrv and VboxUsbMon from 'system' to 'demand'. That failed first time so I tried 'automatic'. Then I did the restart tests again: 8/8 success. Re enable the VboxNetAdp as well... again success!  

Now I had re-enabled all the drivers so I tried running Virtualbox again with complete success. So far I have had no hangs on restart with those two non PnP drivers set to automatic. (See here for an explanation of driver startup types http://technet.microsoft.com/en-us [...] 25630.aspx )  

BTW the checksum on the package is wrong! Oracle have released a new version of the VirtualBox without updating the MD5 page. You can see the release number of the installer is different from that quoted on the checksum page!  

Thanks again - problem solved!

RegExp Q*Bert

I was reading the famous Coding Horror and his comparison between RegExp and Q*Bert languages is very funny and "accurate".

This remains me the post of the new book of RegExp cookbook 2nd ed :

(?:429496729[0-5]|42949672[0-8][0-9]|4294967[01][0-9]{2}|429496[0-6]?[0-9]{3}|42949[0-5][0-9]{4}|4294[0-8][0-9]{5}|429[0-3][0-9]{6}|42[0-8]?[0-9]{7}|4[01][0-9]{8}|3[0-9]{9}|2[2-9][0-9]{8}|21[5-9][0-9]{7}|214[89]?[0-9]{6}|2147[5-9][0-9]{5}|214749[0-9]{4}|214748[4-9][0-9]{3}|2147483?[7-9][0-9]{2}|21474836[5-9][0-9]|214748364[89])

Still I think there must be a better solution for it. Anyone ?

Bobby Fishcer jugando tenis de mesa

Estas fotos de Bobby Fishcer jugando ping-pong son de culto:

Imagenes del documental de HBO: Bobby Fischer Against the World (2011):

Documental de uno de los mas grandes jugadores de ajedrez del mundo, Bobby Fischer. Muestra de forma agil y entretenida la vida inicial de este genio que de forma autodidactitca aprendio y supero las tecnicas de la epoca ajedrecistica.

Entrevistas a los principales actores del gran bullado campeonato del mundo de 1972 contra Spassky. Filmaciones de la epoca y como algo tan lento pudo tomar tanta atencion, que claro que por el tema de la guerra fria, hizo un impacto global.

Despues de llegar a una cuspide insuperable se ve la caid libre de este gran jugador que años despues pudimos ver por enfermedades mentales no tratadas cayo en un decadencia sin retorno. Entrega una triste y real vision de lo que sucedio con él y quizas deja un espacio al libre albedrio para imaginar si hubiese jugado contra Karpov y seguido una vida mas racional.
Curioso detalles es la locura de varios grandes jugadores mencionados en el filme... será un patrón o mera coincidencia ?

Para cuaquier persona que haya jugado a algun nivel o respete este deporte-ciencia, es una manera fresca y dinamica de ver esta biografia del mas grande los los jugadores norteamericanos.