All 11 entries tagged Yajilin

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December 30, 2011

Friday Puzzles #137

Delayed I’m afraid, until I get back from my New Year’s jolly in Budapest – which will mean either next Monday or Tuesday realistically.

In the mean time, thanks for sticking around, and I wish you all the best for the 2012!

And I’m back!

Apologies for the delay in updating this, but if you look at it another way you’ll be getting two puzzles in two days. Which is nice. I haven’t seen many 2012 themed puzzles thus far, so I thought what I’d do is fall back onto a theming favourite, yajilin. I’m actually quite pleased with how this one has turned out out. Enjoy!

#168 Yajlin – rated medium

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All puzzles © Tom Collyer 2009-12

December 09, 2011

Friday Puzzles #134

I was up quite late last night writing puzzles, with the intention of putting up a sudoku puzzle. But apparently I wasn’t quite up to it, and went back to some loop puzzles. I thought yajilin might be a good idea, firstly because I’ve been having a little fun playing with some relatively unknown tricks, and secondly because it gives me a chance to give an alternative presentation another go. I think the way I’m currently rationalising things is that the bordered squares represent holes in the grid, and whether you put clues in these holes is up to you. This works perfectly provided you don’t have too many holes next to each other!

Anyhow, you’ve been spoiled this week, dearest reader, because here are two puzzles to brighten your day. Or something like that. Enjoy!

#164 Yajilin – rated easy

#165 Yajilin – rated hard

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All puzzles © Tom Collyer 2009-11

November 25, 2011

Friday Puzzles #132

So in a previous WPC report entry, I mentioned I’d share what I thought was the pick of the puzzles. Well this is a sort of a pre-emptive strike on that front, because the puzzle I have in mind as the inspiration for this week’s puzzle is an absolute beast of a yajilin. However, rather than being a puzzle during one of the rounds, this was featured on a Japanese newsletter that was being handed round, courtesy of PuzzleTokyo, a society ran by students at the University of Tokyo (こんにちは – here’s hoping google translate isn’t screwing me over!).

What you need to know about this newsletter is that it was entitled “Habanero,” and what you need to know about this puzzle is that in the hotel in Eger I saw puzzlers as good as Byron C and Palmer M sitting and staring at it for quite a long while. And also that I feel happy enough about eventually (no doubt to the amusement of Aga B!) solving it to post a picture of my solution:

It should also be easy enough to recreate the grid if you want to have a go at it yourself. In case I haven’t been clear, be warned. This solves with some absolutely beautiful logic from start to finish, but, easy it certainly ain’t.

On a slightly parallel thread, a couple of days I commented on Para’s blog that he’d hit the jackpot with yajilin presentation. Trust me to go and find an example which then exploits a potential ambiguity in what I thought was so great. As such I’ve made some slight modifications which I don;t think look so bad given the visual theme of the puzzle. Notice that without the arrows in the blank cells, it is ambiguous as to whether R1C1 is a blank clue or simply part of the grid! In a slightly similar vein, the blank clues at R1C7 and R7C1 might just as easily be interpreted – for solving purposes anyway – as cells in the grid to be trivially shaded in. What will we do with yajilin presentations, dearest reader?


#162 Yajilin – rated medium

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All puzzles © Tom Collyer 2009-11

August 26, 2011

Friday Puzzles #119

I’m not sure what to say this week. I wrote this puzzle on a bit of a downer last weekend, and it seems nice enough looking back on it now. When test-solving I used what I thought was a “medium” technique (whatever that means) to get it done, but I suppose it’s more than possible it’s easier than that.

Good luck to anyone doing the USPC this weekend. I suspect one fellow blogger, Thomas Snyder is hungrier than ever to secure yet another consecutive title (and I thoroughly recommend anyone interested in doing the test to check out his “better know the USPC puzzle series”), but he should probably keep an eye open for another fellow blogger, Palmer Mebane. This particular blogger will be hoping to keep mistakes down to a minimum!

#149 Yajilin – rated medium

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June 17, 2011

Friday Puzzles #109

So apparently my brain is rather frazzled today, and whilst there is the makings of a good puzzle idea here, this one is probably a little too symmetric and a little too easy. Also, in other news, I didn’t make any mistakes :D.

Enjoy anyway!

#137 Yajilin – rated easy

FINE stupid blockquote mark-up blog code, don’t work like you have done in a 100-odd other posts. See if I care.

All puzzles © Tom Collyer 2009-11

April 15, 2011

Friday Puzzles #100

So dearest reader, we’ve reached our 100th week.. Of course, it’s not the 100th discrete week I’ve been putting out puzzles, but let’s not trouble ourselves with mere semantics. Obviously week 100 is pretty close to week 104, with the latter being a more concrete milestone in my own eyes, but why pass up a theme like this? Enjoy!

#126 Yajilin – rated medium

All puzzles © Tom Collyer 2009-11

P.S. A big thanks to all the people leaving comments last week who I didn’t find time to reply to. I’m glad the idea went down well with you all!

January 07, 2011

Friday Puzzles #86

A yajilin puzzle this week, dearest reader. Although this is only another little ‘un this week, I am beginning to convince myself it’s harder to squeeze out elegant yajilin in small sizes than it is for larger sizes.

Incidentally, this might have been a candidate for my alternative yajilin presentation (see here and here ) – my first draft has only six non-redundant numbers – although the positioning of each of the clues is actually quite crucial. Still, I like the whole 0/1/2/3 thing I managed to get out of it, so this time it stays in classic yajilin format. Enjoy!

#112 Yajilin – rated medium

All puzzles © Tom Collyer 2009-11

September 10, 2010

Friday Puzzles #69

So this week I’ve decided to keep playing with the alternative presentation of Yajilin. My argument at this stage is that this really isn’t a stand-alone Yajilin variant, and to reply rather lately to the comment MellowMelon made on the last post that yes, I agree that in general it isn’t too hard in filling up the grid with “useless” clues. With this presentation, I could indeed have gone through that process this week, but there are two main reasons why I’m serving you up the following.

Firstly I couldn’t be bothered. What can I say, maybe I’m lazy, maybe I just need the right motivation. But secondly, I think the shaded squares add a certain something to the aesthetic appeal of the puzzle over, let’s face it, is otherwise a rather barren looking grid.

Certainly, this is a different sort of solving experience going on here, working out the claustrophobic implications of the narrow passage ways than you’d see in your average Yajilin puzzle, but I think it must be reiterated that it’s an easy job to put these back into “standard” presentation.

But you’re probably getting bored reading all that, and would much prefer some puzzles to solve. Enjoy!

#084 Yajilin – rated medium

[My apologies for inconsistent and unsolvable early versions of #084. For the record, the top left clue went from being unmarked, to being a 0, and finally to its correct status as a 2:)]

#085 Yajilin – rated medium

All puzzles © Tom Collyer 2009-10

September 03, 2010

Friday Puzzles #68

For this week’s puzzle, I’ve decided to have a little play with Yajilin, and its presentation.

A problem I quickly ran into was with how the clues have an effect on the puzzle. It wasn’t too long into making this that I had a nice symmetric pattern laid out in the grid, and a few clues in place. As I continued putting in more and more clues, it became increasingly obvious that I wasn’t going to need all the marked squares for clues that I’d set aside. However, I also realised that I couldn’t simply throw them away (for one thing, think of the symmetry!). But more importantly, because the rules of Yajilin say that you have to use every square in the grid, these as yet clueless squares were still playing a crucial role in the solving process.

As such I’m going to throw you two versions of the same puzzle, presented slightly differently. For the first, I filled in the the clue squares I needed, sometimes ridiculously, and sometimes a little more obscurely, all the time trying not to introduce too many logical short-cuts into the puzzle.

I am not sure then, that despite having more information in the first version, whether actually the second is a nicer solve.

#083a Yajilin – rated hard

Note in this version that you can shade in a square directly adjacent to a blank grey square, although the loop definitely cannot enter these squares. Also note that the the grey squares aren’t included in the count of the to-be-shaded squares.

I’m hoping I’ve deleted the right clues, although I suppose it’s not the end of the world If I’ve gone too far. I think it should work out that there are probably still one or two technically surplus clues hiding in there.

#083b Yajilin – rated hard

All puzzles © Tom Collyer 2009-10

May 26, 2010

Friday Puzzles #50

So writing a Yajilin puzzle with symmetry gives you all sorts of issues with uniqueness and stuff. Good luck to anyone in the hunt for a symmetric 10×10 with just the four givens! Still, I gave it – symmetry in general that is – my best shot with this one, and I only just failed. Enjoy!

#060 Yajilin – rated medium

All puzzles © Tom Collyer 2009-10


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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Latest comments

  • 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

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