Friday Puzzles #253

Only a mere 6 days late, here's an easy yajilin.  It has the sort of trick that I should probably send to 11 buried in there, but inevitably with a puzzle I penned before collapsing from exhaustion last night there seems to be too many clues.

I have to say I'm considering shutting down the blog until the autumn after tomorrow's post.  We shall see how things go, dearest reader.  Ditto with my contributions to GM puzzles.

For now, enjoy!

    #291 Yajilin – rated easy

All puzzles © Tom Collyer 2009-14.

detuned radio: an update!

So I'm just taking the time to do a little thinking aloud, and update my dearest readers on what they can expect from me as a puzzle maker in the coming year (and beyond!)

Firstly, my main priorities for the next few months lie with the UKPA, and with several major upcoming projects.  First on the list are the UK Sudoku Championships and UK puzzle Championships, as well as hopefully a bit of website work.

I remain committed to the daily league sudoku project, and this will mean that a good chunk of the puzzles on this blog will remain sudoku and variants.  There may be a few other types, but I wouldn't count on it for now.  I'd very much encourage anyone who thinks they might want to get involved, to get involved.  These are the best sudoku puzzles you find anywhere in the world, and they are coming out one a day.  It's something I am very proud of and I hope it'll keep going for as long as possible!

As time allows, I'd like to start organising contributions and putting together a book to sell. There are many things to sort out here, and this is something I certainly won't have any time for until much later this year at the earliest.  You'll have noticed that I've stopped putting together PDF's for the daily league - this job is currently being undertaken by Christof Seeliger, and you can find these files on the facebook group.

Perhaps some of my dearest readers have been a little disappointed that for the last year this blog has almost exclusively dealt in sudoku and variants.  However, I'm sure you are all more than aware that I am currently a "Contributing Puzzlemaster" over at the Art of Puzzles blog.  From now on I intend to put a post on this blog linking to the relevant post whenever one of my contributions appears.  Given my UKPA priorities, this will be sporadic for much of this year, but perhaps it'd be reasonable to expect something at least once every 2-3 weeks from me there.

Whilst talking about Grandmaster Puzzles, it'd be remiss of me not to mention their Patreon page.  The idea here is basically a way to voluntarily provide financial support for a project via a kickstarter-esque mechanism.

I am toying with the idea of setting up my own Patreon page, and I'd like to get some kind of feedback on whether this would piss anyone off.  Let me make this clear: detuned radio will remain free to view and free of any ads as long as I have a nice free platform like blogger that allows me to do so.  Creating puzzles remains a wonderful distraction which is reward enough without beginning to think about any kind of money.

I'm not sure I'd like to promise any Patreon rewards (solutions?  Nice PDF's?) for any theoretical patronage just yet, but it would be nice to give those of my dearest readers who might like to express their generosity the opportunity to discretely do so, without getting in the face of my equally dearest readers who don't.  I'll probably try and discuss this a little more in the next few weeks if I get some positive noises.

Finally, this puzzle needs a home - and given something very similar appeared on GM puzzles yesterday - I can't think of a better place than here as reward for putting up with my ramblings.  Perhaps this should have gone up on the 1st, but whatever.  Enjoy!

    #279 Yajilin – rated medium

All puzzles © Tom Collyer 2009-13.

Friday Puzzles #208

Sorry, I've been busy with other things today/this week.  Expect another yajilin puzzle in the not-too-distant future!

Sorry for the delay.  Easier than last week, but watch your step!

    #245 Yajilin – rated easy

All puzzles © Tom Collyer 2009-13.

Friday Puzzles #207

I'm fairly sure, Dearest Reader, that you won't have seen many yajilin puzzles like this before.  Enjoy!

EDIT: Original posted puzzle had multiple solutions; please see the comments below for the discussion.  First "correction" had a counting error!

    #244 Yajilin – rated medium

All puzzles © Tom Collyer 2009-13.

Friday Puzzles #190

Not much to say this week, I'm stuck in a bit of a rut and have many other things to be doing.  This yajilin probably reflects my general lack of inspiration.  There were some nice ideas which never quite seemed to come together and this is what happened instead.

In other news, t'other Dr. Tom has a new blog (with hopefully more besides to come), and there have also been a lot of excellent sudoku recently courtesy of my good friends Fred and Rishi, if that's more your cup of tea.  You should probably also keep an eye on the links section to the right there, which I'll be updating at some point.

    #227 Yajilin – rated medium

All puzzles © Tom Collyer 2009-13.

Friday Puzzles #154

So I've apparently lost my faith in all of humanity, and most of my all my own self-esteem.  I wanted to spend ages knocking up a really nice yajilin puzzle, and instead this one simply fell out in 15 minutes. Enjoy.

    #185 Yajilin – rated medium

All puzzles © Tom Collyer 2009-12.

Friday Puzzles #145

So in a moment of apparent madness this week, I have decided to forego the pleasures of solving puzzles for the Lent period. I'm a kind of sucker for these sorts of seemingly inexplicable feats of willpower stubbornness, just to see what I'm apparently capable of. In previous years I've done still crazier things, like giving up hot beverages or worse still, shaving but I suspect come 40 days and 40 nights this one will be right up there too.

Anyhow, enough of my more neurotic ramblings.  The upshot of it all is no nikoli.com, no croco, no crosswords, and the horribly scrambled Rubik's cube on my shelf will have to sit there taunting me with its lack of order.  As far as the blog is concerned, whilst writing a puzzle isn't quite the same as solving one, there is obviously a significant overlap, and besides, you'd hope I'd at least be testing the puzzles I put out, right?

Still, I'm never one to pass up the chance to make metaphorical pancakes - or indeed to pass on a vague theme - so earlier this week I hastily put together six puzzles.  The theme will hopefully become apparent.

This week, yajilin, a theming favourite of mine.  I can't remember exactly how hard this is now, but I suspect somewhere between easy and medium.  Enjoy!

EDIT: There was originally a missing clue, which apparently took solutions down from one to none.  This intrigues me!

    #176 Yajilin – rated easy

All puzzles © Tom Collyer 2009-12.

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
 

All puzzles © Tom Collyer 2009-12

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

All puzzles © Tom Collyer 2009-11

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?

Enjoy!

    #162 Yajilin – rated medium

All puzzles © Tom Collyer 2009-11

Friday Puzzles #123

I’m in a little bit of a rush this week, in particular the image quality might be a little below par for now. I also plan on editing in the grand final puzzles from the Times championship last week a bit later, but for now, you’ll have to make do with this yajilin. I think there’s enough here to bump it up to a medium. Enjoy!

    #153 Yajilin – rated medium
(can't find the old image.  Meh.)

EDIT and with alternative Akari-style presentation:

   #153 Yajilin – rated medium

 See also this link for an interactive web version, courtesy of Otto Janko.

All puzzles © Tom Collyer 2009-11

SECOND EDIT And for those who are interested, here are the puzzles from the grand final for the Times Sudoku championship. On the day, these must have taken me 20+ minutes, but when republished in the newspaper later in the week, I clocked 14.10. Perhaps some of that was familiarity, but I’d argue that only made a difference with one of the puzzles (#4). I’d even argue that 14.10 felt a little slow, and as I posted in a comment in the previous entry, I reckon the crème de la crème could be much closer to an aggregate 10 minutes.

As with last year, I don’t have any sort of permission to reproduce these, so I’ll take them down if requested, but no-one complained last year and I think it’s fair use in so much as this will provide highly interesting international comparison. Since there is no copyright in the paper, I can’t be 100% sure that these are from the Puzzler Media generator, but I think it’s more than likely that that’s the case.

    2011 Times Su Doku Championship Grand Final #1
 

    2011 Times Su Doku Championship Grand Final #2
 

    2011 Times Su Doku Championship Grand Final #3
 

And finally, my own personal nemesis – and as with the case with most nemeses there’s no particularly good reason why this would be the case! 

2011 Times Su Doku Championship Grand Final #4

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

All puzzles © Tom Collyer 2009-12.

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.

    #137 Yajilin – rated easy
 

All puzzles © Tom Collyer 2009-11

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!

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

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

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

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

Friday Puzzles #48

Well, I must admit the titling is getting increasingly more weird for me. Anyhow, I’ve been a bit rushed today – and besides the last few puzzles have been pretty hard – so here’s a let up with something I’ve knocked up in my lunch break. This is a fairly gentle Yajilin puzzle. If you’ve never come across this type of puzzle before, then let me point you to the left hand side of the page where you’ll find a “how to play” section. When I first came across it, I thought (unless the puzzle was really gentle) that it was pretty easy to make a mistake. Hopefully with this one it’s easy to see where you’re going on a global scale and it’ll all fall into place nicely. Enjoy!

    #058 Yajilin – rated easy

All puzzles © Tom Collyer 2009-10