Difficult Sudoku

I blogged about Foxtrot and Sudoku a while ago and it garnered a lot of interest. Given that, I thought folks may be interested in some difficult traditional sudoku puzzles I have come across.



The way I actually determine difficulty is from a program I wrote that solves the puzzles. The program implements a number of techniques to solve the puzzles and determines how hard it is based on the techniques that must be used and how quickly it can be solved. I hope to have the solver hosted where you can get to it soon, so stay tuned.



In any case, here is the hardest puzzle I have come across.

7 9 1     8	1 7	4 8   2
6 7	5 9   7 3	7 6
2   8 6	9 5	6     1 2 9

And another difficult one.

4   5       2 1	2	2   9         7 3
7 3         4	1   9       5   2	5         1 3
7 8         9   1	7	6 5       7   4

Give them a try!

More on Linux or Unix

Ok, I recently blogged about Solaris being unfairly portrayed along with the "other" Unix vendors, and I now see that Sun/Solaris is being portrayed as less open and flexible than IBM and AIX!



In another SearchOpenSource column the author this time talks about how moving from Sun to IBM would give more flexibility because IBM's POWER5 architecture supports both Unix (AIX) and Linux. He does this while completely ignoring that Sun's SunFire line of hardware not only supports Unix (Solaris) and Linux, but also Windows, giving more flexibility than IBM's solution.



He also ignores that Solaris is open source and that it runs on industry standard hardware giving customers even more flexibility by not being locked in to a single hardware vendors.



The scenario is couched as being "hypothetical" but grossly misrepresenting the real facts should not be stood for.

Linux or Unix

I am subscribed to a bunch of technology news newsletters, one from SearchOpenSource.com that is generally informative and interesting. However, an article they had recently on Linux or Unix was missing some info that I just have to comment on.



The article highlights the pluses and minuses of both Unix and Linux, but it only speaks generally about Unix and groups Solaris, HP-UX, and AIX together. Given what Sun has done with Solaris over the past few years this is a mistake and paints an unrealistic picture of where Solaris is today.



First, the article says flexibility is a downside of Unix highlighting that Linux is open source and "you actually have the source to the kernel, and if you have the knowledge, you can actually make the changes yourself!". Hello, are they not aware that Solaris is also open source?



Next it dings Unix on price saying that companies must buy a license to a proprietary Unix and then pay for maintenance on top of that. Hello again, but are they not aware that Solaris can be downloaded for free? Yes, if a company wants to be supported they can purchase a license and support but they are not required to.



Then it mentions difficulties in a company separating from a specific vendor due to lock in due in large part to the operating system only running on hardware from that vendor. Hello yet again, are they not aware that Solaris runs and is supported on commodity (Sun and non-Sun) x86/x64 hardware? There are over 700 x86/x64 systems on the Hardware Compatibility List.



The article goes on to highlight as advantages how Linux doesn't have some of the issues above and those are similiarly incorrect when comparing with Solaris.



Does Linux have a place in corporate environments. Sure, but not for the reasons identified above.

FoxTrot and Sudoku

I'm a big fan of the comic strip FoxTrot and today's strip is classic.

In it, Jason (the geeky youngest child) creates his own Sudoku game where instead of having numeric clues to start, the clues are various different math problems. There are square roots, cube roots, numbers in base 2 and hexadecimal, summations, integrals, and more. His sister aptly calls it "Sudorku".

Well, being a huge Sudoku fan and a bit of a geek myself, I had to try to solve it. First, I got to do all the math and dust off a little of gray matter that hadn't seen the light of day in a while (product management doesn't require integrals very often :)). Then it was a pretty straight forward Sudoku solution of medium to hard difficulty.

I've also recently started doing Killer Sudoku which adds a new twist to things. There are actually a few different variations, one that starts with no starting numbers as clues, but instead adjacent cells are grouped and a sum of those cells is indicated. In another there are no numbers at all and instead cells within a 3x3 box have a > or < between them indicating whether the values is greater or less than each other. And then they have a combination of the two.

Try them and have fun!

The other side of the world

I recently had the privilege of traveling to India for business and it was a fantastic experience, ... other than the travel!



Getting there took 36 hours of travel time and getting home took 27. Everything in between went very well. And to be honest, the Changi Airport in Singapore really is a nice place to have a layover with lots of shops and free internet available. I was able to get a little work done and using Skype, make a few calls home during my layovers.



On the trip, I had the opportunity to meet with other folks from Sun as well as a number of partners to talk about integration, SOA, composite applications, and the Sun Java Composite Application Platform Suite.



I also had the opportunity to participate in a 3 city event on "How IT fosters Enterprise Agility" put on by the Jasubhai Group where I spoke on how identity management and SOA are key components of an agile enterprise, and how Sun provides products for this with Java CAPS and the Sun Java Identity Management Suite.



Thanks to my hosts that knew just the right places to go, I also had the chance to experience the myriad different cuisines in India.



All in all, a great trip. If only it wasn't so far away.