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08 February 2009 @ 05:55 pm
The Art of Sudoku - Competition Edition (2)  
I don't write many classic sudoku (in part because computers seem to have "solved" that problem for most domestic sources), but I sometimes dream that a newspaper may decide it wants to become, for sudoku, what the New York Times is for crosswords - ie "THE Source" for the popular number puzzle with the best examples. If any newspaper ever materialized for such puzzles, this is what a week of my sudoku might look like, using the seven puzzles I wrote for today's sudoku competition at the 3rd Silicon Valley Puzzle Day.

The first three are the youth puzzles, with "Spiral" being my favorite with a powerful visual theme I have not seen other constructors use yet. The next three starting with "Little Boxes" and going through "Crosshairs", the hardest of the seven - the Saturday puzzle I guess - are the qualifying round puzzles for the adults. The fastest three adults over all three rounds got to compete on the "Winner's Trophy", which has a nice shape and two additional thematic elements (the single 1 in the givens being set specifically in the center to signify the winner's label on the trophy, and the reverse psychology test of the top row given a 2-8 ordering of the middle cells).

For those that care, and think I can fairly report times on my own puzzles, this set of numbers is my standard {1'17", 1'39", 1'25", 1'56", 2'13", 3'30", 2'17"}. Those times are not necessarily representative of how I perceived their difficulty, but the outlier Crosshairs certainly has the narrowest, most difficult solving path. I'm a firm believer that moderate-hard puzzles (without unnecessary things like Y-wings) can segregate solvers and so that philosophy is at play here. I was hoping the best solvers would average ~2-3x my times or ~6 minutes per puzzle and this was certainly true, with a majority of solvers able to finish each puzzle within the time-limit.

More talented solvers made the trip this year than last time, when Eric Maddy from Southern California came and won both the Sudoku and Crossword tournaments and was the main "ringer". This year, while rpipuzzleguy was a judge with me and therefore not a "ringer" in either of the tournaments, Derek Kisman and US sudoku champion onigame both showed up to compete and I thought they'd do well. Derek lost on a tiebreaker from making the top three. While Wei-Hwa's paper times were not the best in the room, Wei-Hwa has an impeccable "vertical solving strategy" for final round puzzles and ended up winning easily once he made the final puzzle. Given the difficulty of solving a large-format sudoku on an easel, I specifically tried to have the final puzzle be easier than what preceded it; still, the other two finalists (including last year's champ Eric Maddy) made some errors and could not finish within the time-limit. With the bad experience that the beginner/intermediate finalists had at Philly last year also breaking their grids, I think it is worth considering retiring the 3+ foot "puzzle for the check" format, at least for one year to see if its the "stress" of competing for the trophy versus the change in format from paper, that leads to the much worse solving results.
( 5 comments — Leave a comment )
(Anonymous) on February 9th, 2009 09:08 am (UTC)
Very nice. One of these days I'm going to do a couple of my own, I have a couple of (what I think are) good ideas for solving themes. A big thanks for that countdown blog you did a few weeks back!

And yes it is unfair to give times for your own puzzles :p - unless you give people at least 3 go's at solving them to get them familiar with the nuances. I'll do them later today when I wake up properly.

(Anonymous) on February 9th, 2009 03:24 pm (UTC)
my times - which were fairly consistent it must be said:

1.44, 1.25, 1.30, 2.37, 2.35, 2.44, 2.23
thedan on February 10th, 2009 02:28 am (UTC)
Interestingly, in each batch of three, the third puzzle was my fastest. (I see that for the first batch that wasn't your slowest, but I came within a few seconds of your time on the Windmill, which is highly unusual for me). I think I'm just so accustomed to solving tough puzzles these days that I tend to look for subtle things first and overlook obvious placements on easy puzzles.

Very nice puzzles, but I expect nothing less. Now let's have some kenken, please. I hear they're the way of the future.
motrismotris on February 10th, 2009 02:31 am (UTC)
I like the digit 8 too much to write normal KenKen that apparently are too hard to go above 6. Although I guess a variation in a 6x6 box where you don't know what 6 integers are being used is up my alley. You know I'm a fan of Lost, right?
(Anonymous) on March 23rd, 2013 03:48 pm (UTC)
( 5 comments — Leave a comment )