Log in

03 December 2009 @ 09:27 pm
Friday Puzzle #26 - Sudoku Cup 3 - Arrow Sudoku Example  
There are many goals one should have in preparing puzzles for a championship.

For my upcoming Sudoku Cup, my goals are to achieve my trademark "cool" looking grids while also having fun, fair, logical solves for the purposes of a competition. Another goal organizers should have (but often fail with) is to provide example puzzles for all types, and ideally sample puzzles of similar difficulty. I've decided a reasonable way to achieve this is to make 2x the number of puzzles I need of a type, test them both, and pick the one that works best for the competition but use the other as an example. Both puzzles were constructed with the competition in mind, so they should be reasonably representative of each other, but may be slightly harder or easier and I won't say which.

This is the path I'm taking (so far) for January's Sudoku Cup. The next few Friday Puzzles will contain some of the "lesser" members of each constructed pair, and will eventually make up a sample test/instructions.

This week, I'm showing my favorite current sudoku variation, which I've made a few of for Sudoku Masterpieces. Its another Arrow Sudoku, as in Friday Puzzle #5. I hope this (and the examples to come) whet your appetite for the competition.

Rules: Fill in the cells with the digits 1 to 9 so that each digit appears exactly once in each row, column, and bold region. Digits in the circled cells represent the sum of all digits along the path that the arrow travels. Digits can repeat within a sum, but cannot otherwise violate the no repeat rules for a row/column/bold region.

(Anonymous) on December 4th, 2009 05:12 am (UTC)
Do you take requests?
Here's a variation on an idea I have for a sudoku. Arrange it so that each square has (the base ten representation of) its own number from 1 through 9 and the numerical square of it, read horizontally. (So 1, 5, and 6 are problematic; just include their squares, but each 3x3 square should have one of 2, 4 or 3, 9, or 4,16, etc., up to 9,81. If you wanted to cheat and have three rows like
there might be an artistic license for that.

And, of course, there is the symbol form of sudoku. Perhaps you could
make one that had a 3x3 emoticon made from ASCII as the center block.

Gerhard Paseman, 2009.12.03
motrismotris on December 4th, 2009 05:31 am (UTC)
Re: Do you take requests?
I certainly see ways to get all the first 9 squares into a classic grid (I'd say number and its square touching is a much better choice than same box since 1/5/6 fail otherwise). The real challenge will be having a single solution after getting those 24 digits in there. I tried for about 5 minutes and realize it would take me more time than I have now to accomplish this interesting theme.
(Anonymous) on December 4th, 2009 05:30 pm (UTC)

A very nice puzzle. Liked the spiral pattern. Can appreciate this much more easily than any pattern with givens, which tends to pass me by, especially when I'm timing myself. I'm afraid that I won't be free on the Saturday when your Sudokucup puzzles are being solved but I'm sure that it will be a great contest.

By the way, I also liked the multi-operation Kenken puzzles 2/3 weeks ago. Very aesthetically pleasing.

I have read most of the What if? series. I'm afraid I don't have time to engage at the intensity that you and others manage. I try to be competitive and I was frustrated by how poorly I did in Zilina. However, I'll try to erase that from my memory when Philadelphia comes around. You will be missed if you hang up your solving hat for good. Hopefully, time will heal and you can rediscover the fun of championships. I think the reuniting of the WPC and WSC will be a major plus.

Will you be at the ECS meeting in Vancouver next spring? It falls just before the WSC.

David McNeill.

motrismotris on December 4th, 2009 06:01 pm (UTC)
Glad you liked the puzzles. And even outside of the competition time I hope you get a chance to do the SudokuCup as intended and can see your level on my puzzles.

Re: What If? I'm not sure I even have the time for the level of debate that's going on, but if anything is clear, it is that Zilina showed us that without competition standards there will be failures to even have sudoku at a sudoku championship, let alone solvable puzzles.

If I have a particular problem with the WPF and its lack of standards, and it is exacerbated by the Zilina non-response after what can happen given this lack of structure, then I really do not feel it is fair to pick and choose which of the competitions to go to, to signal to the US or Japan or Germany that I trust them and to other nations that I don't. I simply have to stop competing until changes are actually made (or a new organization supplants this one).

If sudoku competitions are dead to me, why do the USSC this year then? Well, I went to that tournament to try to publicize a book of my sudoku that had come out the week before, a book that is miles better than any of the ABC (asymmetric, bland, computer-generated) Sudoku you can find out on the shelves. Despite always holding this book throughout the championship, despite being a focus of all reporters, despite being a loud voice if not the voice of the solvers against Eugene's cheating which was obvious to me if not immediately to the organizers, Mutant Sudoku received little meaningful coverage. I do not see, even in a puzzle publishing sense, any value in competing in these "sudoku" and sudoku competitions any more.

I enjoy writing puzzles, recently I've hated solving sudoku, and if this is how I feel and I have only so much time outside of my bioengineering research to do puzzles, I'm going to shift to 90+% construction than 50:50 solve and write. I'm sick of spending time getting better at bifurcation, especially if the best solvers don't tend to win the championships that run, when there are meaningful things to be doing with my time.

Edited at 2009-12-04 06:20 pm (UTC)
(Anonymous) on December 7th, 2009 08:55 pm (UTC)
The sudokucup will be available the whole weekend (16.-17.1.2010). So if you have time you can try it on Sunday :o)

Karel Tesař
nickbaxternickbaxter on December 4th, 2009 09:10 pm (UTC)
Great puzzle. And if this is a "reject", then the competition is going to be pretty awesome.
motrismotris on December 4th, 2009 09:55 pm (UTC)
What can I say? I liked the other one more.

There is a reason I like Arrow Sudoku so much and I think puzzles like this capture why. While most arrow puzzles randomly spew the arrows, and this can lead to nice properties, arrow puzzles with some structure can have even more interesting things happen.
yureklis on December 4th, 2009 10:54 pm (UTC)
That was nice. I have solved about 20 minutes, i didnt realize some arrangements, some restrictiones that was caused by possibilities of digits are included by sums.

As you know i made a lot of Arrow Sudoku's, i really like this puzzle type. Thanks to JNPC for the sudoku type. I didnt make Arrow Sudoku's based on any construction, but it looks like very nice. I like spiral construction. Thank you for the puzzle.
(Anonymous) on December 5th, 2009 09:47 pm (UTC)
Very nice grid !

I like it even if I did a very stupid mistake 1rst time I try to solve it !
(I hope mistakes are good now so perhaps I'll not make them during competition lol )

(Anonymous) on December 6th, 2009 01:17 am (UTC)
This puzzle rocks. Took me 25 minutes but I'm just a half decent solver.

Uwe Wiedemann from germany wrote some "Bagua Sudoku" for our last championship. I don't know what Bagua means, but basicly it's an Arrow Sudoku where you don't know which field of the line contains the sum. There are also some (rather hard) puzzles of this type in the german puzzle portal.
(Anonymous) on December 6th, 2009 01:57 pm (UTC)
I think bagua sudoku don't contain any sum in it (except bagua killer for example), so in my opinion bagua are not really like arrow sudoku.

Here is an example of bagua sudoku:


(Anonymous) on December 6th, 2009 04:05 pm (UTC)
OK sorry, I was actually talking about "Sum Line Sudoku".
motrismotris on December 6th, 2009 07:57 pm (UTC)
I've lost track of Uwe's puzzles in the last 3 years, in part because there were so many of such variable solving quality as he first became prolific, and in part because he never linked back to my collection of sudoku puzzles despite using my Mini-Fleet and Battleship Sudoku recipes a long time ago.

Sum Line Sudoku is certainly what you meant, and it is an interesting twist of the formula, but even with allowing bent lines like in an arrow, I still really prefer the anchoring the arrow form gives, at least for constructing puzzles with "big" and "small" cell type thinking.