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04 February 2008 @ 10:42 pm
Art of Sudoku, Competition Edition  
I wrote an earlier article on The Art of Sudoku and this combined a lot of the puzzles (including variants) that I'd written at that time that I really liked. Well, this past weekend, I provided the puzzles (and also gave a puzzle solving and puzzle constructing lecture!) at the 2nd Silicon Valley Puzzle Day. I wrote seven puzzles with graphical themes for the event and they are all included below the fold. The first three, my main theme expression over three separate puzzles, were for the adults. The fourth is the championship puzzle solved on stage. Then, some easier puzzles follow which are from the youth division. I think I hit the sweet spot of difficulty pretty well for the adults, so the first solvers would be at about 7 minutes in each 20 minute round, but most people would only solve or be close to solving by the time ran out. My only consideration for next year (if I can provide puzzles again) is if I should have a more staggered set of difficulties - which might call for a similar staggering of round times. Any comments from competitors who happen on this site are definitely welcome.

Adult Puzzles:

Adult Final (on placard):

Youth Puzzles:

knightwizard on February 5th, 2008 08:09 am (UTC)
I really like the first one...looks like you got the Atomic number and weight in :-)

I'll have to print these out and give them a go at some point. They definitely look they could keep me busy for about 10 minutes each.
thedan on February 5th, 2008 08:25 pm (UTC)
My times, in case anybody else is in training and wants something to compare to:

Silicon - 4:02
Valley - 4:09
Puzzled, Eh? - 4:58
Race for FIRST - 5:21
Tic-Tac-Toe - 2:00
Four Square - 3:05
Have A Nice Day - 1:38

Very smooth constructions, Thomas. Sounds like it was a fun competition.
motrismotris on February 6th, 2008 02:39 am (UTC)
It's good to see that your times (much like Wei-Hwa's), seem to be a simple scalar multiple of where I'm at, and so I can gauge expected difficulty for top solvers in a useful way. Wei-Hwa's had to do this in reverse, as he wrote puzzles for the Stanford film project and needed to get things that should take me 1-2 or 2-3 minutes.

It was an interesting event, in that it combines a sudoku tournament and a crossword tournament (using this week's M-Th NYT puzzles) as well as rooms with games and a puzzle/book sales area and a set of talks. If you want to hear Byron Walden talk about constructing and solving hard crosswords, this is the only event where I know that to happen. I similarly gave my first talk on solving and constructing sudoku and hope it was informative to those who attended. The main problem as I see it is location, with its being on the other side of San Jose from where I'm taking away almost all potential San Francisco attention as its a 70 minute drive.
thedan on February 6th, 2008 08:32 pm (UTC)
I'm betting Wei-Hwa's scalar multiple is lower than mine. :)
motrismotris on February 6th, 2008 08:45 pm (UTC)
No comment, but your times are very good.
lunchboylunchboy on February 6th, 2008 02:40 pm (UTC)
Have only done the first four, but --

Silicon: 9:30 (probably would've been faster if I hadn't been standing up on the subway and making a transfer in the middle of solving)
Valley: 7:29 (still standing)
Puzzled, Eh?: 6:23 (sitting down now, finally)
Race for First: 4:29 (on the subway platform later)
Emilydumble on February 6th, 2008 11:52 am (UTC)
I probably should have introduced myself earlier, but better late than never. I found your livejournal when looking for commentary on this year's Mystery Hunt. (I was participating remotely on an extremely flaky internet connection, so I was able to get a general sense of how it went but not to be nearly as involved as I would have liked.) I like reading people's thoughts on puzzles of all sorts, hence my interest in your journal!
knightwizard on February 7th, 2008 05:46 am (UTC)
Definitely a larger scalar than Thedan...
Here are my times:

Silicon: 11:43 (messed up...twice!)
Valley: 6:15
Puzzled, Eh?: 8:55
The Race for FIRST!: 6:23
Tic-Tac-Toe: 3:26
Four Square: 10:50
Have a Nice Day: 3:48

Silicon I simply made mistakes. Four Square, however, pointed out flaws in my solving technique. I generally associate numbers with rows or columns in the 3x3 boxes, which didn't seem to work for this one. You address your solving technique in a later post, so that seems like a good place to start to work on improving my solving technique.

The puzzles were quite fun. Thanks!
(Anonymous) on February 8th, 2008 02:13 pm (UTC)
Re: Definitely a larger scalar than Thedan...
My times:
Silicon 5:51
Valley 6:38
Puzzled, Eh? 7:26
The Race for FIRST! 6:38
Tic-Tac-Toe (oh, my eyes :/) 2:30
Four Square 4:42
Have a Nice Day! 2:24
(Anonymous) on April 4th, 2008 05:19 am (UTC)
My times
1. Silicon - 11:55
2. Valley - 12:13
3. Puzzled - 13:15
4. Race for First - 9:42
5. Tic-Tac-Toe - 5:20
6. Four Square - 6:10
7. Have a nice day - 4:29

Can you suggest some manner in which I can solve Sudoku faster? The only thing that I can think of is solving them again and again (going over the ones that I have already solved).
motrismotris on April 4th, 2008 06:06 pm (UTC)
I've found the key skills to be faster at sudoku are to improve on your pencilmarks and to be able to switch between looking by digit (here are 1's, so where are other 1's, ...) to looking by geometry (what row/column/box is almost full - what is missing - what can go there) and going back and forth efficiently. Also, when I place a digit, I'm checking for other occurences of that same digit I just forced, but also any other digits in that row/column/box that I could place as progress tends to lead to progress.

I have a Youtube video series with some puzzles you can watch me solve, as well as hear me explain some things I'm thinking about when solving them. It might be worth printing out those puzzles, giving them a try, then comparing to how I do it.
(Anonymous) on April 6th, 2008 10:55 am (UTC)
Thanks for the reply.
The approach that I usually take is to try to write down where each digit can go, in the process filling those places where one and only one digit can go. This requires meet to several digits in each of the squares and then crossing them out. Now I have started avoiding crossing the digits. This I hope will cut down the time taken.

Adam R. Wood: butasanzotmeister on July 22nd, 2008 04:38 am (UTC)
In case anyone is wondering why I decided to "join the dark side" (Nick Baxter's words) and invalidate myself from competition:

Silicon: 9:55 (beautiful logic patterns in this one)
Valley: 19:39 (stumbled on the '1's something fierce)
Puzzled, Eh?: 36:31 (just kept screwing it up)
The Race for FIRST!: 10:13 (lagged on the left)
Tic-Tac-Toe: 4:24 (I need to learn to count to 9 faster)
Four Square: 9:28 (five minutes of which was me realizing I didn't screw up)
Have a Nice Day!: 3:02 (nice border)

- ZM
(Anonymous) on August 16th, 2008 11:42 pm (UTC)
very nice puzzles, thank you (just found you). have you written any killer sudokus?

Silicon - 9:27
Valley - 6:55
Puzzled, Eh - 13.44 (oh, yes)
The Race for First - 6:56
Tic-Tac-Toe - 3:50
Four Square - 7:18
Have a Nice Day - 10:42 (relaxed too much and made big mistake)
motrismotris on August 16th, 2008 11:47 pm (UTC)
I haven't written any killer sudoku that are posted on this blog. However you can find another sudoku variation that requires a good amount of arithmetic logic in Paint By Number Place and I also have a bunch of kakuro variations listed here with a list of my other puzzles.
(Anonymous) on August 17th, 2008 03:35 am (UTC)
I´ll try them out. Thank´s a lot.

what is your opion on killer sudoku versus ordinary sudoku, kakuro and others? just curious to hear because I tend to like them more. unless you compete on time or against somebody I think ordinary sudoku isn´t as diverting and consuming as the killers.
motrismotris on August 17th, 2008 04:00 am (UTC)
Killer sudoku are fun puzzles (although I prefer Nikoli Kakuro to any source's killer sudoku).

The competitions I do either use just classic sudoku (like the US Sudoku Championship) or classic + variations (like the World Sudoku Championship) and I greatly prefer the formats that includes variations. There are only so many techniques to use on the classic puzzle, but getting a new ripple where you need to figure out how to use strategies you know from the classic in a new situation is what is enjoyable about puzzling. I obviously still do ordinary sudoku when practicing for championships, but when I'm choosing a puzzle to solve for fun, it is more likely a variation of sudoku or another type of puzzle entirely.
(Anonymous) on August 17th, 2008 04:22 am (UTC)
I´m going to look into the nikoli kakuro thing - because I have a hard time finding enough killers that are fun. there are only a few websites that have them everyday and they are mostly too easy. I have all the books.

I think the problem with classic sudoku is that you can mostly solve them pretty quickly. I love a good killer that takes time.

thank´s for giving your opinion - wish you best of luck in your next competition.

(Anonymous) on December 7th, 2012 06:05 pm (UTC)
Silicon : 5:07
Valley : 5:18
Puzzled eh : 9:14
Race for first : 4:58
Tic tac toe : 3:39
Four Square : 3:46
Have a nice day : 2:01

Sudoku sure runs in your blood motris :) i enjoyed solving a lot ,great flow in all sudokus.Wish you would write art of puzzles part ii.Almost completed your part one.A very good sudoku book
motrismotris on December 7th, 2012 06:12 pm (UTC)
Re: Timings
Thanks for your comments.

Do you mean art of sudoku II? I actually intend my next book to be an art of puzzles book with more than just sudoku but will get back to sudoku titles eventually.