Very nice puzzle set. My favorite had to be the Shikaku. Thanks Tom!

With no more participants at this time, Nikoli Selection 2011 is over.

We'll take few more hours to review some of the wrong submissions, but the positions in top 10 will not change.

Congratulation to Hideaki Jo (all 19 puzzles), Thomas Snyder (18 puzzles), NAGATA Yuta (17 puzzles) for topping this test.

Indian results are not very encouraging, Rohan, Amit and Rajesh take top 3 spots.

Total 215 players participated, out of which 168 got non zero scores. This is easily the most that participated in any LMI 2011 puzzle test.

Detailed score with submission timings now available - as usual - at http://logicmastersindia.com/M201107P1/score.asp

Mind boggling performance from Hideaki Jo - he finished 3 marathons in about 42 minutes.
Apart from Thomas, volxa also finished 2 marathons, but with 2 mistakes.

Lot of players finished all Main section puzzles, and many more getting close to finishing them.

Thank you everyone for participating, and making this successful.

Thanks Tom for providing a very entertaining puzzle set, I'm sure everyone had some favourites among them. My personal favourites are LITS, SHIKAKU, NURIKABE and AKARI.

It was not surprising to see that 5 out of top 8 players are from Japan (just like last time). Of course, some players from German were missing, may be because of German Puzzle Championship on Saturday.

Yes, makes sense to put that information in the submission page itself. Will do that for future tests.

One funny quirk I'd like to point on the Kakuro: on the solving route I took, I had most of the lower-left to upper-right diagonal after a short amount of work, basically dividing the rest of the puzzle into two halves with only one blank cell in common. I noticed that the answer entry only looked at the upper half, so I applied the usual "row sums minus column sums" logic to get that blank cell and finished with basically half of the puzzle unsolved. In general I think one should avoid marking rows/columns on the edge of the puzzle if at all possible, since otherwise you're prone to allowing this kind of thing.

MellowMelon: I was fairly confident the solving route had to go something like bottom left -> bottom right (via some work on the lower diagonal) -> top right -> bottom left (via the other diagonal) and then finally end up in the top left. Nothing like this was mentioned in the test solving, although I am always a little wary about concentrating solution keys in one area. There were a couple of other puzzles as well where I thought something like that could plausibly happen, but again I don't think this affected many solvers. It's definitely something I'll think about more in the future.

Thanks all for taking part and for generally leaving such kind comments. I'm very glad that this contest went through without any hitches like last time, and really impressed with some of the scores. Motris actually had the main 16 out faster than deu (and indeed faster than I had managed to test solve my own damn puzzles!), but as I raised the point earlier on in the thread, if player X gets more of the marathons out than player Y then X is indeed the worthy winner in my eyes. I had thought it'd be impossible to get all 3 marathons out and was truly astonished to see that deu had managed it.

I hope there weren't too many people who were in the situation of finishing the main set but unable to get 1 marathon out - actually I think all things considered even getting the main 16 out entails a seriously good performance. Of course, the vast majority of solvers *didn't* finish the set, so I hope there was something in this test for everyone, and that you enjoy the remaining puzzles without any extra competitive stress.

Finally, thanks again to Deb for running the show seemingly effortlessly, and to Rakesh and David for testing.

For Suraromu, the answer key required the number of turns.
For row A, I submitted 5 turns, since I thought the 'turn' at the starting/finishing point is more of a 'make ends meet' as opposed to a turn.

Nice set of puzzles Tom, I liked LITS best.

I'm already as slow as a snail on puzzles, so when I also make mistakes...

I thought I'd add some puzzle specific comments now - specifically the oddities that made me laugh a bit:

For the second straight test, Tom actually wrote a LIT puzzle, not a LITS puzzle. But I was happy that the answer entry this time used the tetromino shape Tom is deathly afraid of (must have eliminated it from memory after bad Tetris experiences?).

I also appreciated the "not 2-9" row of the Kakuro which riffed on my 1-9 complaint from the last Kakuro Marathon. I did sort of expect the change though so had no problem resolving that corner which certainly just feeds as Melon points out one digit to the upper-left. For most Kakuro I like diagonal entries as the USPC does, but I'm not sure with the strong lower-left to upper-right diagonal if this would be an improvement on this puzzle. Probably two long rows and/or two long columns that target both isolated sides as opposed to a mix of rows/columns that only hits one.

After breezing through the actual test, I got caught with a small mistake on a huge puzzle of a type I don't enjoy solving. And tweaking a mistake in a large puzzle is a whole different challenge from just erasing and restarting as in a small one. While the small Yajilin used some nice loop properties, the big one in my opinion was just long albeit with a nice symmetric pattern. I couldn't recover enough to finish it within 90 minutes (100 minutes is a different story). Fortunately I switched to completing the Heyawake in time to not completely botch the second contest. Still, if there are to be marathons next time, I'd prefer more balanced scoring so solvers can go after them at any time. It is odd that deu and I both competed in some other test after the first one ended in 45 minutes. Congrats to H.Jo for his marathon solving ability; I'd obviously used up too much energy expecting the contest to be a sprint and lost in the last miles of some different race.

Edited by motris 2011-07-11 3:04 PM

This obviously wasn't Nikola Selection .

Great performance of top two players, I haven't even got to see a marathon puzzles. Time was up in front of my eyes when I try to enter last "regular" puzzle. However, I will keep this test in my memory because here was one beautiful puzzle - suraromu.

Nikola

Thanks for a great contest!
In Nikoli magazine and Nikoli.com puzzles, some difficult techniques are not used.
So, at least for me, this contest was a good chance to solve Nikoli puzzles which never appears on Nikoli
(Yajilin (small) and Fillomino are typical examples).

As for my performance, I feel very satisfied to achieve what author did not expect.
After entering and checking my 16 answers, I had 40 minutes to solve three marathon puzzles.
When I solved Heyawake in 12 minutes, I became convinced that there was enough possibility of finishing all puzzles if I made no mistakes.

It was a nice contest, and there was something for everyone. And this one turned out much better than the first edition. I hope Nikoli Selection 2012 will be even grander.

Congratulations to everyone who finished all 16 from the main section. They are all winners of this contest. And special congratulations to those who managed to solve even one marathon !!!

From the main section, I liked Nurikabe, Hitori, Shikaku, and, of course, Suraromu.

Very fun test, with some really good puzzles. Nice sudoku, excellent suramoru, ripple effect and LIT(s), amongst others.

I made some stupid tactical choices, like wasting the last 10' on the Hashi, a puzzle I dislike, instead of solving the Numberlink and checking my Fillomino on which I was almost sure of having done something bad - and indeed, I had. But all in all, a satisfying performance for me.

Thanks Tom, and big congrats to Hideaki for such an impressive performance.

I agree, very fun puzzles. During the contest I had to rely a little bit on intuition on some puzzles (the Yajilin which I've solved properly afterwards, the Fillomino where I should probably have summed up the clues at some point, and also the Nurikabe. I still need to revisit that one.

Just now I looked at the marathon Heyawake, and was wondering if anyone else is having trouble with uniqueness? I solved it properly until just a patch in the bottom right and the top right are not filled in. Aside from room 'B' which is still open, my solution agrees with the correct code. It looks like the bottom right should close up so that connectivity forces a path along the right edge, forcing the top right including B=1, but I think I have a valid solution with B=2…

Most likely I'm missing some wrong room count or three-room violation, but I really can't find any at the moment. (A uniqueness argument forces B=1, so there's a very small chance an ambiguity would have been missed in the tournament.)

Edited by rob 2011-07-13 2:47 AM

I shall post a solution...give me a sec to do it in paint :)

Here we go - not quite in Hideaki's time, but I did have to faff around uploading and stuff!

http://www.warwick.ac.uk/~marear/36x20_heyawake_abc_solution.PNG

Thanks, that helped! A 4-room some distance away had just three black cells… I'll give it a fresh try tomorrow.