Friday, 30 September 2011

Friday Puzzles #124

I’m afraid this week’s puzzle is also going to be a bit delayed, new laptop and all, perhaps until later tomorrow. Whatever happened to my time management!?

EDIT: After much delay, here is the puzzle. It’s another Nurikabe, a type for which I don’t think I’ve quite nailed my own individual style. On the other hand it means that I come up with lots of slightly quirky puzzles. But then I don’t know exactly how I should be rating them. I think for the sake of beginners I’ll leave this as a medium. Enjoy!
    #154 Nurikabe – rated medium
All puzzles © Tom Collyer 2009-11

Friday, 23 September 2011

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

Sunday, 18 September 2011

2011 Times sudoku championship

Time for a “quick” and rather sleep deprived write-up of the championship – if I don’t do it now then it’ll end up like the Beijing tournament where I never quite get around to doing it.

First off, I suppose I should offer a little explanation as to why I now refer to this competition as the Times championship rather than the UK championship. This is because the UKPA now has had two competitions calling themselves UK championships, and as WPF representatives have a more authoritative claim on being able to award a national title. Even if the Times event has more participants, glamour and shiny trophies!

Anyhow, semantics and pedantry aside, onto the report. Coming into the event I was feeling really quite confident in my classic sudoku solving times, and believed that if I could go through the championships without making a mistake, then there’d be at least a 50% chance Times title would be mine for a 3rd time. Obviously there’d be some strong competitors, and with a grand final format when anyone from 8 can take the title inevitably a little chance comes into things, but I thought I had an edge and as such could see little point worrying about things being a lottery.

The day itself started with a minor panic. Registration for the event was between 10.00 and 10.45am, with the 1st preliminary round kicking off at 11.00am. I’d got on the 8.50 train from Coventry to London Euston, due to get in about an hour later, thinking that another hour would be plenty of time to make it over to the News International building near Tower Hill. I had not counted on the signalling issues which had left the train still in the middle of countryside at 10.00am, delayed by about 20 minutes, so that when I arrived at Euston I was a bit of a fluster. I briefly headed down to the underground station, was greeted by a lack of funds on my oyster card together with a monstrous queue for tickets, before biting the bullet and getting a taxi to take me to Thomas More Square, near Tower Hill (as opposed to the one in Hackney – more on this later!)

I passed through the security and went up the lift at about 10.50, with little more time than to appreciate the spectacular views looking down onto the Thames and beyond, say a quick few hellos to some familiar faces (Mike Colloby; George Danker and his parents Martin and Max) as well as some less familiar faces whose names I recognise from the UKPA forums – David Collison and Rodderick Grafton.

At this stage I will have to make my apologies. Lots of lovely people came over and mentioned that they read my blog, which was really quite flattering. Unfortunately I don’t think I’m able to list everyone individually here. Suffice to say I really appreciated all the kind comments people gave me, and I hope you enjoyed the competition!

Anyhow, onto the first preliminary session. I think I was still a bit shaky as I went to tackle the first puzzle, because whilst apparently cruising through it I’d manage to make some sort of screw-up towards the end of the solve. I tried briefly to fix my error, before remembering the lessons of last year’s competition. Rubber out, start again. As is often the way when you restart a puzzle, progress often seems slower, but I plodded my way through and was on my way. The remaining 3 puzzles solved very smoothly though, and when I was done I managed to look round and see George Danker and Nina Pell still working, so I thought I’d afford myself the luxury of a couple of minutes checking. Everything still seemed good, and I turned in. As it happened, even with 5+ minutes wasted from the first puzzle I had still turned in 2nd in the room, behind someone I hadn’t come across before, Gareth Fuller. The usual suspects of George and Nina were also shortly done.

I should at this stage describe the agony of turning in your solutions very early, when you have as prolific a track record as mine of making Dickhead Errors. When I solve for pleasure, I’m always certain I have the right answer because I don’t guess and I have full faith in the processes of reason and logic. I don’t know my exact times, but I’d guess it was well over 40 minutes and it’s not a fun thing to sit there in silence, glancing round at the room and generally praying that you haven’t made a mistake.

Thankfully it turned out that I hadn’t, but I was still a little shaky heading into the short break – a good proportion of my cup of tea ended up in the saucer as apparently my hands weren’t in the most steady of states. Again there were lots of people who I was talking to but I couldn’t really focus on any one conversation. I suddenly realised that there was no sign of my good friend Rishi Puri. I called him up and it transpired that Rishi had made it all the way to the other Thomas More square, but he was hopefully of making it in time to watch the finals.

Onto the second preliminaries. I think it’s safe to say I nailed this, clean solves all the way through, and even after another extended checking period it was still a few more minutes until Nina was second in the room to hand in. Again more agonising in silence for what seemed like an absolute age, but at the end, the results were announced, and I was the best qualifier for the grand finals, having finished the two preliminaries perfectly with the 2nd and 1st quickest times. If I hadn’t already had enough confidence in my abilities, then I couldn’t really argue with these facts.

There was an hours break for lunch, and again I tried to get hold of Rishi – he’d made it as far as Tower Hill but couldn’t find anyone to direct him to Thomas More square. I put him over on the phone to Martin, who is a London cabbie, and sure enough with his calm directions on board, Rishi was there at reception just as I was heading out to pick up a sandwich from the nearby Waitrose.

Quick aside – the Waitrose BLT is really good!

And so onto the grand final. As the best qualifier, I had my pick of the 2x formation of seats. I’ve had this discussion with Thomas Snyder who argues there is an advantage to choosing a seat at the back because it gives you an idea of what your competition is doing – in particular if you have time to do a quick check. My own take on the matter is to simply bury myself into my own world – for this reason I like to take the front seats. If I really believed I was quickest, then anything anyone else was doing would only serve as a distraction. The other qualifies in order were: Nina, George, Mark Goodliffe (the serial Times crossword champion), Gareth Fuller, Matt Cannon, Kit Collingwood and Mary O’Connor.

Onto the puzzles themselves then. Puzzle #1 solved pretty smoothly, and judging by the lack of paper turning noises I was the quickest to get this done. Next up (due to the quirks of the folds in the booklet) was puzzle #4. I was making fairly solid progress through the puzzle, spotted some fairly subtle things which had given me some numbers in what appeared to be sticking points, and generally was under the impression that the puzzle was about to fall. And then I hit a sticking point. I put in some extra pencil-marks in the hope that I’d just missed a pair or something, but nothing doing. OK, fine, onto puzzles #2 and #3. These solved fairly quickly and without hiccup, so back to number 4.

Still nothing. So I’m half a puzzle from victory, so why not take a guess!? (Because you are terrible at guessing?). I try something and it doesn’t get me anywhere. A little erasing and start again. And then Mark Goodliffe declares! Panic! I try another guess and again nothing doing. Another declaration is made. Shiiiiiiiiiit! Shitshitshit! I decide to do the sensible thing and go nuclear with the rubber again. I get to the same stage I was at. Another declaration. ARRGHH! Still stuck. And then I bloody well see it. With a digits in R9C5 and R8C6 and a fixed pair in R9C4 and R9C6, the 8’s in the 4th column and the 5th column trivially forced the 8 to go in R7C6. How the bloody hell had I managed to miss something so bleedingly obvious!? I literally took my palm and applied it to my face. And then filled out the remaining half of the puzzle in about half a minute, as my self-directed rage propelled a flurry of solving. I was resigned to not winning as I saw George was one of those who had declared before me. The other was Matt Cannon.

It seemed obvious to me that Mark Goodliffe had again applied the same all-or-nothing approach to guessing as he had last year – and had as such hopefully made a mistake. I know Mark will probably be reading this, so I hope he doesn’t take too much offence when I say that the puzzles in the final in my opinion weren’t at the difficulty needed to needed for guessing and it would be highly unsatisfactory to me if a title was won on the basis of serial guesswork. Of course I fully understand his position – Mark is the first to admit that whilst he is certainly a pretty good sudoku solver, he isn’t quite at the fastest level, and as such his strategy gives him the best chance of winning. From his point of view it is a no-brainer and I fully respect that! It is certainly nothing personal to Mark when I say that I hope it doesn’t come off for him whilst the final puzzles remain at the difficulty that they do.

As it happened, serial guesswork is probably an exaggeration as he said he guessed only on 2 of the puzzles (as opposed to all 4 last year). Nevertheless a point of interest was raised whilst we waited for the final results to be confirmed. George, sitting in front of Mark, had apparently inferred by the fact Mark had turned in first that guessing was required for the last puzzle, and had taken his own guess to ensure quick progress to the end. This was exactly the position I was in, so it’d be highly hypocritical of me to pass any judgement here. If I’m right in remembering (and please correct me here) I think Matt had also said he’d guessed and that he’d probably made a mistake.

The results came back, and as I suspected, Mark had made a mistake – but the rest of the 7 had solved perfectly, which handed George his 2nd consecutive Times championship. I was left to rue missing something so blatantly obvious that had cost me in the order of 5 minutes. I could apparently afford to do that in the first preliminary round, but as I said to George, with solvers as good as he is around you can’t afford to throw away 5 minutes and expect to win. My congratulations go out to him!

The rest of the competition had me sat in my same chair in a strange state of frustration/annoyance/acceptance, as we continued the post mortem. The two solvers closest to me were Matt Cannon and Kit Collingwood – both it turns out relatively new to the competition and put everything into refreshing perspective. If you are reading, it was good to meet you!

The presentation was handled seamlessly by David Levy, and the trophy was handed to George by Andrew Stuart, author and owner of the excellent Scanraid/sudoku wiki website. I think he was pleasantly surprised when chatting afterwards that I (and numerous other top international sudoku solvers) regard scanraid as THE objective sudoku grading resource. He is more focussed on the solving strategies required to solve the sort of fiendishly difficult classics that I (and numerous other top international solvers) believe have no place in competition, yet still occasionally crop up. He very kindly gave me a copy of his book, detailing some of these strategies. I think it says it all that the techniques I draw the line at before guessing myself – x-wings/swordfish and y-wings – were detailed very early on in the book!

And with that, we said our good-byes, and I headed to the pub with Rishi and Mike. I think I’ve still got a bit of an inner-conflict going with my feelings about the championship and my own personal performance, but looking at things more objectively it was great to see some old friends, even better to meet some new ones, and a pleasure to indulge for a day with a large group of enthusiasts who share the same passion as I do. See you all next year – I will be hungrier than ever!

Friday, 16 September 2011

Friday Puzzles #122

Wow – an entry on time? Who’d have thought it?

This Sudoku puzzle felt like more of a medium last night, but I think it’s probably like most of my other Sudoku puzzles, disappointingly easy. Anyway, I think this is a great grid pattern and it solves very cleanly indeed.

Good luck to anyone coming down to London tomorrow for the Times “Su Doku” championship – I shall be doing my best to not make any stupid mistakes, again.

There are also a multitude of other competitions going on this weekend too, this time on the interwebs. Maybe I’ll be able to squeeze some time in this weekend to replace my printer cartridge? Maybe I’ll be sick of the sight of any sort of 9×9 grid. Anyhow, keep tabs on all things competitive puzzling via this link:

All that remains to say is enjoy – and if you are feeling competitive, try for a sub 3 minute solve. If you are feeling really competitive, below 2 should also be doable.
    #152 Sudoku – rated easy
All puzzles © Tom Collyer 2009-11

Wednesday, 14 September 2011

Friday Puzzles #121

Again, I can only apologise for the lateness of this post. Rest assured I’ll be in the country both on Thursday evening, and on Friday, so the next post will be on time.

This Heyawake is the the culmination of a few ideas I incoherently put together at quarter to one this morning. With a larger size, I reckon this could be developed into a more “complete” puzzle, but hopefully there are a couple of interesting quirks with this one. Enjoy!
    #151 Heyawake – rated medium
All puzzles © Tom Collyer 2009-11

Wednesday, 7 September 2011

Friday Puzzles #120

Apologies all, I was away on conference last Friday, and I’ve still not got around to putting up a puzzle. Hopefully you can expect last week’s puzzle up here later on today!

EDIT (Thursday): Well what a surprise, turns out I did have a semi-decent Masyu lying deep in the pile. For tomorrow’s puzzle I had planned to do a Slalom again, but I’m not sure I will have time as I’ll be back on the road. Maybe expect something that next Monday, or else I guess it’ll be something a little more tame if I can get something done today. Enjoy!
    #150 Masyu – rated easy
All puzzles © Tom Collyer 2009-11

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