SudokuSolver Forum

All sudoku puzzles in this forum post are the intellectual property of Børge Alexander Tetlie Anderssen.
Copyright © 2008 Børge Alexander Tetlie Anderssen.  All rights reserved.  Terms of Use.

Here we have the by far best Sudoku forum known to mankind, and we do not have a single Vanilla Sudoku
Probably says something about the geeky members here

So to take us back to the roots, I generated 3 Vanilla Sudokus, and since Skyscrapers seem to be so popular ...





000730504000000000500000120020009608081003400000200000000410000600008000090002706





000000005300900700008000010050009400060000000410007030005080090940005000000004601





000007104000300000040005280500000301030000902004070000800930000000010460002000000

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Well, I THOUGHT I was going to have a vanilla sudoku to post today (generated completely by hand by me), but it turned out to have 185 solutions. Back to the drawing board!

(I had forgotten to bring my puzzles with me to my children's music lessons, so I was looking for something to keep me from fidgeting. . .)

And I was hoping you were going to surprise us with a ROAG (Root Of All Gattai)

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Oh, yeah, THAT'll be the day!!! Who do you think I am? Ruud?

Wow Børge. If I were you I'd put that huge pic (325kB, 4193x1809 pixels) inside a "hide" box or as a link through a smaller thumbnail.

Also, I counted 16*11+15*10=326 grids for this setup, so what's up with the grid count of 295 at the right?

Finally, since you bring this up, I'll share this one puzzle generated by JSudoku which takes a special technique called "Strong Wing" to solve (for those who don't like forcing chains):

You probably need strong wings to reach the sky limit.

Added later:

Of the 3 puzzles Børge posted, the first two each takes a skyscraper but the 3rd takes a single xy-wing to solve (together with the basic techniques of singles, subsets, box-lines).

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A ROAG is 16*10 + 15*9 = 295 grids. When assembling the various screen shots I did a mistake I have corrected it now.

I use the ROAG for testing the scaling and speed of some of my generation algorithms. After I have released the first version of my puzzle generator helper, I will make I second version allowing you to run the built-in Naked/Hidden Singles solver after initial puzzle generation. This should cause about 60-70% of the dispensable clues to be set as deleted, speeding up the final "more manual" generation stage. Then I should be able to generate a ROAG solvable with Naked/Hidden Singles only, but you probably do not want it to be more difficult.

An @ enxio27: Blow it up to a 12' by 8' poster and post it on wall allowing several people to solve different parts simultaneously. Could be a nice party gag finally getting you fame in the neighborhood.


Certainly NOT. It is meant to be -ing

Can't keep that big mouth of yours shut!


Here is another "fairly easy" one along the same solving path. Making far more difficult puzzles is not the problem.



102008000000700000307600890000000000003006570061000903040050010008007000600009200

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Quis custodiet ipsos custodes?

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My bad. I promise to be more subtle next time!

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ADYFNC HJPLI BVSM GgK Oa m

Yeah, right! That kind of fame I don't need!

Thanks for getting this forum started, Børge.

BTW, do we really have to switch to hidden text to discuss any of the techniques used? The gurus over at sudocue.net never did that with the Daily Nightmare forum. Hiding text takes a lot of the fun away IMHO. It's a bit different on the Killer forum here, because we tend to publish detailed walkthroughs, and thus need to be given the time to do that.

Therefore, I'll keep my comments general for now:

Firstly, I would advise against an over-reliance on a specific software solver, which especially applies in the case of JSudoku and advanced vanilla. As enxio27 already pointed out somewhere on this forum, JSudoku was originally designed for solving Killers. Having said that, Jean-Christophe has clearly been working hard recently to iron out some of its weaknesses in this area (for example, by building in ALS-XZ, Sue de Coq, Finned X-Wing/Swordfish and Uniqueness Test solvers). But there are still some things I'm asking myself, like:

1. Why JSudoku places Skyscrapers so high in the default priority sequence, even above XY-Wings (for example)? I personally would expect most solvers to try XY-Wings first.
2. I note that some Skyscrapers found by JSudoku are based on conjugate pairs all the way round (i.e. strong link used as weak link in the middle). AFAIAA, most vanilla solvers would report this as Simple Coloring.

Lastly, how does one reset the solver sequence to default in JSudoku (I'm using version 1.3b1). I naiively expected to find something like a "Restore defaults" option on the context menu for the solver page.

P.S. @udosuk: What's a "Strong Wing"? Sorry, but I haven't got the time or energy these days to guess and/or re-invent the wheel!

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Cheers,
Mike

Here is the link to the forum discussion I recently started:

http://www.sudoku.com/boards/viewtopic.php?t=6111

However it contains spoilers on how to solve the puzzle I cited above. Just a warning.

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