## June 10, 2011

### Friday Puzzles #108

So in the midst of my triple posting last week, I managed to put out a completely broken Sudoku puzzle, where I’d presumably mistyped one of the digits. Looking back a bit later, I realised it was broken but couldn’t find the dodgy digit, so I went back and changed it.

Anyway, more Sudoku today. This weekend is the UKPA’s Sudoku championship – and I have taken the liberty to put together an example of one of the featured Sudoku variants.

Incidentally, if you want to participate, UK citizen or otherwise, then you should definitely read the instruction booklet and the discussion thread. To actually take part in the test, you will have to be a registered member of the the UKPA forums. Registration is free and easy!

Anyhow, back to the variant. This one has the rather inelegant name of “No Donkey Step Sudoku” – perhaps when I have a free moment (haha) I’ll try and think of something better. Anyhow, the idea is fairly simple. Classic Sudoku rules as you know and love them, with the additional constraint that digits may not repeat within 2 cells on a diagonal line at 45 degrees. If you are familiar with no-touch sudoku, then this is simply a slight extension of the constraint. If you still don’t get it, have a look at my good friend Rishi Puri’s example, which has the advantage of coming with a solution grid. Enjoy!

#136 No Donkey Step Sudoku – rated medium

All puzzles © Tom Collyer 2009-11

### 3 comments by 1 or more people

1. #### Ours brun

Well, the name was originally intended as a joke, and the rule was written in a fun way, explaining that a donkey is somewhat moody ; so, he sometimes walks this way (1 cell in a direction, then 1 cell orthogonally), and sometimes that way (2 cells in a direction, then 2 cells orthogonally). I didn’t expect other authors to seize the idea and create some other puzzles of this same type. Which is great, but these authors didn’t keep the fun part, and so I understand that the puzzle’s name does appear a bit strange now. Still, I am really pleased that this variant has some fans – and by the way, I am gonna copy out this puzzle and try it right now.

Bastien

10 Jun 2011, 17:26

2. #### Ours brun

Done. I found it very easy (the puzzle can nearly be solved by using only the untouch rule), but nice. Certainly better than my first attempt of this variant.

Bastien

12 Jun 2011, 23:20

3. It’s true, there are 23 givens and that probably seems like a lot in retrospect. I think I posted medium because I linked to this from the UK forums, and this isn’t really a variant that many people doing the championship this weekend will likely have come across.

Actually the pattern of givens is quite interesting. I wonder if I can manage to get a classic puzzle to work with them…

12 Jun 2011, 23:35

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## Information

Welcome to the blog of current UKPA sudoku champion, two-time Times national sudoku champion and general logic puzzle fan Tom Collyer.

Home of the original Friday Puzzles, each Friday I publish a 100% original and handmade logic puzzle, inspired by the world-famous Nikoli company.

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• I like the appearance of the solution. :P Nice one. by Prasanna Seshadri on this entry
• I think I've seen something vaguely similar in some of Palmer's puzzles as well. To be honest I've a… by on this entry
• That's two puzzles in a row where I find something I had used before. I know, not plagiarism; just g… by Bram on this entry
• Kota, that's not really true. I had made my puzzle before going to the WPC already. Also I don't hav… by Bram on this entry
• About 20 minutes, after restarting from a mistaken conclusion. by Bryce Herdt on this entry