## Wednesday, May 18, 2005

### Sudoku

Sudoku is a relatively new puzzle. In its current form it was developed two decades ago by a Japanese publishing house. The word means "number single". The rules of the game are very easy:

There's a 9x9 box consisting of nine 3x3 boxes. You need to fill in the box so that every row, every column, and every 3x3 box contains the digits 1 through 9.
As the Sudoku webpage says: "That's all there is to it. It's fun. It's challenging. It's addictive!" Here's a sample question. (This is also the May 2005 contest puzzle at http://www.sudoku.com/. You could solve and submit the answer here.)
Sudoku is in the news everywhere these days. In the UK, it's become a national craze apparently. Times, Daily Mail, Daily Telegraph, Guardian, Independent, and the Sun offer Sudoku puzzles to the readers. "Forget the election, the Royal wedding and Beckham. A puzzle has national newspapers - and readers - in its grasp", wrote the Independent. (Here's a detailed article from the Guardian about Sudoku.)

I do think it's interesting, but I do not understand the hype. Perhaps when one's absolutely bored, and in no mood to blog, one could attempt Sudoku! Anyway try it out once. It might take 5-10 minutes.

Update (May 23): Dion Church, a Telegraph sudoku enthusiast, has come up with 'the ultimate Sudoku', a 3-D version of Sudoku. It's called the Dion Cube. All the rules apply but now in three dimensions. Here's the first Telegraph Dion Cube.

Update (May 31): Jerome Turner has a blog -- Sudokusolution -- devoted to Sudoku. Two other interesting sites here and here.

At 11:14 PM,  Dilip D'Souza said...

Yo Anand, solved that, took about 15 minutes. A lot of fun. I love these kinds of puzzles.

At 11:46 PM,  Anand said...

Yeah this stuff does take time. Yesterday I tried a couple, and each took almost 20 minutes. The Daily Telegraph has a Sudoku archive with puzzles of reasonable difficulty.

But Dilip, I'm a bit worried when you say you like Sudoku. Now some of us might start objecting that there's no logic in Sudoku, the solution doesn't follow from the starting premises, etc!

At 7:53 AM,  Dilip D'Souza said...

Come on Anand, first let's get the most important thing of all clear here: is it "premiss" or "premise" or "premmis" or "premmiss"? You want to talk about logic, you have to pick on the spellllling firrrrst.

At 7:20 PM,  Anonymous said...

Who are you, Dilip... to talk about other people spelling mistakes (or not)? This a blog that is meant to be fun... It's for people who like to enjoy themselves with Sudoku puzzles... If you have are in a bad mood just go elsewhere and let us here solve our puzzles in peace.

At 8:41 PM,  Dilip D'Souza said...

Anand, solved this one (you remember in our email exchange I found I had solved the one on the sudoku.com page); made one inexplicable mistake, but after restarting it went fine. How would they be more difficult, I wonder?

And I think what we discussed last Sunday, about what would be a minimum number of initial entries to produce a unique solution, would be an intriguing problem. Any thoughts on tackling it? Then there are other interesting problems: if you have one less than that minimum number, do you have two solutions? Or more? Etc.

All in all, fun stuff! Thanks for introducing me to it. I might put up some puzzles in a future science post...

At 10:08 PM,  Anand said...

Thanks Dilip. That question doesn't seem to have an easy answer, right?

It'll be nice to see related stuff on your blog as well. I was also thinking of another post detailing how I reach the solution. This thought is prompted by the Google search strings that take people to this post.

At 3:26 PM,  Matt said...

Lo Anand, I'm pretty into the whole sudoku scene. My friends and I wrote a mobile version you can play on most phones now.
It's only £3 for 90 puzzles.
http://www.sudokumobile.net

At 1:09 AM,  Dave said...

Thanks for your blog! You might want to check out Web Sudoku which lets your play online.

At 5:21 AM,  Akshay said...

These things are very interesting. Just solved one.
Anyway I did some further reading on them. There is a very interesting wikipedia article about them [here].It also has a link to the japanese magazine that publishes them. I also checked out there other puzzles Kakro and Nurikabe.
I bet there are many such types of puzzles in Vedic Mathematics,some body should dig them up.

At 2:35 PM,  Anonymous said...

Hi,

I got hooked as well and have now developed a Suduko Assistant, here:

www.sudoku-san.com

It's intended to be an Assistant, rather than just a Solver (although it can solve them too!). It has four Daily puzzles, and the Assistant itself can be used to keep track of your work, check how you're getting on and make sensible suggestions about techniques you can use to find the next step.

Hope you like it - I'd love to hear any feedback you might have.

cheers,
Alastair

At 2:21 AM,  Sudoku said...

Hi mates, If you like Sudoku puzzles this link has a lot of them, free, and online:
Sudoku

Cheers:)

At 10:06 PM,  Anonymous said...

Yet another blatant plug for a new online solver site:

http://www.sudokuhints.com

Has daily graded puzzles, vague and more definite hints, single step and full solving. Pencilmarks can be shown or hidden. Any position can be bookmarked. Has 3 different size grids so you can choose the best for your screen resolution.

At 3:32 AM,  Anonymous said...

hey

I use this Sudoku site for its excellent newsletter they give daily Sudoku to your mail, and u can get the answers from the site, it is very easy to use,
At www.daily-sudoku.com

At 6:27 AM,  Anonymous said...

At 7:40 PM,  Anonymous said...

Great sites. Be sure to check out Essential Guide and Links to SuDoku for access to a whole internet of SuDoku!

At 6:59 AM,  Anonymous said...

check out http://www.yogi.net/sudoku

At 2:35 PM,  xander said...

Please visit The Sudoku Biglist for over 270 links to sudoku puzzles, solvers, helpers, generators, forums and more...

At 7:22 PM,  Watch free online TV said...

http://www.sudokupuzzles.org/

Free easy and expert sudoku puzzles online. Sudoku, a seemingly simple numbers game, has become the biggest puzzle craze to hit the world since Rubik's Cube.

SudokuPuzzles.org

http://www.sudokupuzzles.org

At 10:22 AM,  Cross Sums (kakro) said...

About the min number of Hints to make a puzzle, theoritically it is 8. It cant be explained easily, but I know it is eight. (if you have eight diffrent numbers placed in the right positions then you will be able to find the nineth one.) If you have anything less than eight (say 7), there will be multiple solutions based on how many numbers are missing.

Now, I dont like sudoku puzzles much, since I happen to create a much lovelier puzzle called Cross Sums http://syndicate.yoogi.com/cross-sums/

These puzzles appears on ThinaMalar (tamil newspaper). You can also try out the free computer game on my site.
http://syndicate.yoogi.com/cross-sums/

At 5:24 AM,  Anonymous said...

I've been doing these puzzles for a few months (and am still picking up techniques!). After making a lot of mistakes using pencil and paper, and having to start again from scratch, I now use this helper (wot I wrote) instead...

www.sudokumate.com

It's a free online helper not a solver (no fun in that).

Any feedback (errors/improvements/etc.) welcome.

Neil

At 8:47 AM,  Kakuro Puzzle said...

Yeah sudoku is great. It was invented by Nikoli. Everyone seems to be ignoring their trademark!

Try Kakuro too:

http://www.kakuropuzzle.com

At 3:54 PM,  Reviewer said...

We're definitely addicted to Sudoku in this family. Here's a new Daily Sudoku puzzle that has Sudoku levels for kids and adults so we can all play, save games, etc.

At 8:15 PM,  Anonymous said...

here's a site for you:

www.sudokubrainteaserpuzzles.com

At 8:21 PM,  Anonymous said...

Sudoku Brain Teaser Puzzles Shopping Center

I meant to mention the shopping center when I posted the website above:

www.sudokubrainteaserpuzzles.com

The shopping center is the most complete one Ive seen on this subject.

Wayne

At 11:01 AM,  Anonymous said...

Checkout http://www.Printsudoku.com. It's a new website where you can find lots of sudokus in pdf format, and also you can play online. There is also Magic Sudokus. This site rocks!

At 8:11 AM,  Anonymous said...

Hei to all Sudoku-Fans, there is a new Challange! Check out Fillomino, it's even more complicated to solve than Sudoku!

At 9:31 AM,  eli_bm said...

Hi!. In www.sudoku.org.es you will find 2 sudoku solvers made with Java. The first one is for normal sudoku and the second one can solve the hardest sudoku killer. Have fun!

At 5:32 PM,  sudokushop said...

What a great blog!

You might want to check out sudokushop which has loads of sudoku related products.

At 1:39 PM,  James said...

Try www.puzzlesbyemail.com, which sends free sudoku puzzles daily. New blog is just up and running, at blog.puzzlesbyemail.com.

At 8:11 AM,  Anonymous said...

This game is like crack or heroin for the intelligent person. 9 numbers, your brains, it's insane!

If you do sudoku, you fall in one of two categories.

1) Addicted, you can't be helped
2) Waiting to be addicted, you can't be helped.

Sort of like the borg, you will be assimilated..... LOL

So if your additcion is getting to you, it is time for SA!

http://www.sudokuanonymous.com

Good Luck

At 1:47 PM,  Willy said...

Hello,

Perhaps it's easy to pay 3£ on a site and download several grids ?

I play on a nice website
DAILY SUDOKU PUZZLE

Have fun !
Bye
W.

At 8:44 AM,  blandi said...

I've recently seen Sudoku-Underware! I think soon there is a Sudku-version of everything you can imagine..

At 4:10 PM,  Anonymous said...

you should check out kakuro its a lot of fun!

At 9:08 AM,  Anonymous said...

Why not putting a real sudoku game (not just an image) in your blog?

Here's how:
http://www.logicando.net:84/viewtopic.php?t=49

(sorry if I'm annoying you).

At 3:40 PM,  Anonymous said...

you should check this
free online sudoku
for more sudoku puzzles

At 11:53 PM,  AndreL said...

Also in french "Sudoku Assisté par Ordinateur " jeu gratuit Excel.

At 8:31 AM,  Arnaud said...

At 1:21 PM,  Chrit said...

Good post. The puzzles get a lot more fun as you manage to get them done more quickly. I found a bunch of puzzles at Sudoku Puzzle / Sudoku Puzzles

At 3:05 PM,  Havard said...

Hi! We have made a little sudoku program you might be interested in! It will let you hand-make (create) your own sudoku, in addition to having a lot of fun ways of solving them. Give it a try and let us know what you think of it! :) www.sudoku.frihost.net regards, Havard

At 9:52 PM,  Sudoku-Fan said...

Hi there, is it true that microsoft will integrate sudoku into the operating system ?

At 2:09 AM,  KristinW said...

Have you tried Samurai Sudoku?

At 2:46 PM,  Seb said...

If you want to play in french, try this flash website : Le Sudoku

At 9:35 AM,  Anonymous said...

I'm a sudoku gan too and I have made a blog where I publish three daily sudokus with different difficulty levels. I also publish different kinds of sudokus, like samurai sudoku,... Hope you like it.

At 12:34 PM,  Anonymous said...

salut
je voulez vous faire partager ma passion le sudoku
j'ai découvert un site ce week end
www.sudoku-gratuit.fr
on peut télécharger pleins de grilles gratuitement(plus de 2000)
de plus on peux jouer en ligne au sudoku
et ce que j'ai trouver super c que le webmaster a mis aussi pleins de truc et astuce pour résoudre les grilles
aller vite sur www.sudoku-gratuit.fr si vous êtes accros comme moi ;o)

At 10:41 PM,  AndreL said...

"Computer Aided Sudoku Excel" includes :
- SURPRISES when your solve a sudoku without help
- generator or puzzles to print
- helper, fast solver
- HISTORIC wich records all the plays. Partial replay.
- CLINIC where you can analyse your Sudoku
Enjoy playing this Sudoku Excel free game on your computer

At 8:19 PM,  Only Sudoku said...

I think I must be slow today it took me 25 minutes to do that one

Sudoku Puzzles

At 8:31 PM,  Anonymous said...

Here's a site that will generate 50 puzzles at a time in pdf format that you can print out. it can make up to 50 puzzles at a time, with either 1 or 4 puzzles per page. It also has 4 difficulty settings.

http://www.opensky.ca/~jdhildeb/software/sudokugen/

by the way, if anyone finds something like this for kakuro, please post, I can't find one anywhere.

sorry.... forgot to put the address in

At 4:58 AM,  carine said...

Hi here's a new sudoku site : http://www.sudokuz.eu

It's about sudoku kid and sudoku prints

At 12:52 PM,  Mochek said...

This is more visually interesting sudoku game.

www.veryfreesudoku.com

At 12:46 AM,  Sudoku said...

Hi!

Another sudoku wepage.

http://sudoku.arrelnet.com

At 2:28 PM,  Anonymous said...

Here it is.
The first
Sudoku Jigsaw Solver

At 8:57 AM,  gridrat said...

Hi guys i've just found a fab new grid game.SHENDOKU can be played with 2 or more friends which makes it alot more interesting. Aswell as a wide range of games they've also got some cool xmas cards and other gadgets. Check it out at www.shendoku.com

At 6:57 PM,  Dave said...

Just in time for Valentine's Day - personalsudoku.com
and get a personalized puzzle or use the permalink feature to email
a puzzle to that special someone!

At 6:15 AM,  sink100 said...

Play sudoku online .
http://sink100.hp.infoseek.co.jp/english/sudoku.html

At 9:04 AM,  armando said...

If you want to try out something new in sudoku, try shendoku, using the sudoku rules but playing two people, one against the other, like battleshipps. They have a free version to download at http://www.shendoku.com/sample.pdf . Anything else they are bringing out or they are working on you can find at www.shendoku.com or at they´r blog www.shendoku.blogspot.com . Have fun, I am. I specially like one slogan I heard about Shendoku: SUDOKU is like masturbation (one person)…. SHENDOKU is like sex (it takes two).

At 11:35 AM,  Kate said...

I found this site very helpful when I was learning how to play sudoku. I'm not sure if you're interested in watching how to videos, but these are great for beginners.

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At 9:18 PM,  carolina said...

You should visit http://www.domo-sudoku.com if you are a sudoku addict. Very challenging brain teasers for kids or adults there.
Cheers