Wednesday 16 February 2022

Results: Sudoku Design Competition

Here's what you've all been waiting for dearest reader, the big reveal!

Firstly, in a completely randomly generated order, here are your (mostly) esteemed and highly talented authors.  I will be in touch over the next few days about the best way to send over the prizes.

Entry A - 0403 came courtesy of Yunus Emre Büyükkale
Entry B - 3233 came courtesy of Tom Collyer (yes, that use of the word "mostly" is there for a reason)
Entry C - 4235 came courtesy of Anuraag Sahay
Entry D - 4438 came courtesy of Jiri Hrdina
Entry E - 5308 came courtesy of Sinchai Rungsangrattanakul
Entry F - 5617 came courtesy of Yoshi Baroshi
Entry G - 6071 came courtesy of Kumaresan R
Entry H - 6283 came courtesy of Gareth Moore
Entry I - 7408 came courtesy of Florian Wortmann
Entry J - 7704 came courtesy of tamz29
Entry K - 9133 came courtesy of Sam Cappleman-Lynes
Entry L - 9158 came courtesy of Jack Lance

[I will edit in a link to a permanent page on this blog to showcase the entries in all their glory, as well as update the PDF.  For now the puzzles can be found:]
I have to say that I went to great lengths to draw up entries as soon I received them to anonymise them and leave until after the closing date, so that I had the best chance of not knowing whose puzzle I was solving as I was going through.  The original idea with 3 picks for me was to roughly group into an easy, medium and hard puzzle, but it didn't quite work out that way in the end.  The first three £25 prizes go to:
  • Entry D - Jiri Hrdina
I thought this was a wonderfully smooth-solving easy puzzle, setting up the obvious hidden pairs in boxes 2, 4, 6 and 8.  These boxes together with box 5 then resolve themselves leaving the corners of the puzzle to be mopped up via some more hidden single.  The sort of highly polished easy puzzle I really appreciate!
  • Entry H - Gareth Moore
I thought this puzzle moved away from an easy level in a very pleasing way, nicely setting up a naked triple half-way through the solve; this was definitely something that set this puzzle apart for me.  

But don't just take my word for it, one very experienced sudoku solver thought that:
H - clearly a favourite. It has a nice solving path, not too easy / not ridiculously hard. ... It would be a good puzzle for the WSC finals or something.
  • Entry L - Jack Lance
Last but certainly not least, as soon as I saw entry L I knew I had a winner on my hands.  The symmetry of this puzzle is absolutely stunning with consecutive pairs arranged in Battenberg formation around the grid, attached to another consecutive pair for good measure.  However what I find most pleasing about the symmetry is that it doesn't fall into the pastiched trap of a Gurth's Theorem situation where you only get to solve half (or even a quarter) of a puzzle.  Crucially with this puzzle different given digits in the grid are not rotational symmetric from other given digits, which breaks the symmetry and ensures the puzzle maintains an interesting, albeit easier solve.  Absolutely beautiful - this is the single puzzle from the set that I wish I had written and in my eyes is now *the* definitive puzzle for this layout.  For whatever that is worth :-)

Finally, the last £25 went down to the public vote.  My previous post announced that I would be disregarding votes from the authors themselves, but in the end this made no difference to the overall winner.  Which is:
  • Entry G - Kumaresan R
Interestingly my dearest readers plumped for one of the Extra Hard puzzles, which i think neatly wraps up the set of prizes (I should add I had picked my favourites before I counted the votes - in theory an entry could have one two prizes).  It must be said Extra Hard in this case comes with a bit of a health warning - you can use a uniqueness technique to turn this puzzle into a much smoother solve, however knowing that some solvers prefer not to use uniqueness if they can help it, this was how I felt I had to rate the puzzle.

The author had this to say about the puzzle: 
Actually it is not hard but an advance technique is involved. Without this technique unique rectangle can be used to complete the puzzle.
Whilst another solver said:
The puzzle I preferred requires a very unusual way of uniqueness, which once found solves the puzzle. Not sure for the 10/10 rating for difficulty since it was an easy spot, but surely 10/10 of cleverness!
Narrowly losing out in the public vote (regardless of whether author votes were taken into account or not) were entries H and F.  We've already discussed entry H, but entry F was the other Extra Hard entry from the set, and perhaps demonstrates that there is something of an appetite for more difficult puzzles.

That's it for now - congratulations to all the participants and especially the 4 winners!  I'll probably look to do some more of these fixed layout competitions with other puzzle style in the future, as I think it went down well with both those who submitted a puzzle as well as those who voted on them.  


  1. Thanks Tom and the public who voted for me. Also thanks the authors who were participated in the contest. Really surprise to me this is the first ever I received a prize in an sudoku event that too an international forum.
    With best,
    Kumaresan R

  2. Aesthetic appeal often plays key when not much separates the solves. I was too lazy to squeeze into any aesthetic value (or did I? it did have a trivial pattern that I am not sure was noticed).
    I understand your fears about the Gurth's theorem situation you mentioned, but I don't recall having to solve a puzzle or a Sudoku that was so awkwardly redundant.
    Entry L and the likes may have began with all the odds of winning the majority, but glad you salvaged it by including in your pick.


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