Puzzle 174: Slitherlink (Unequal Lengths), and Russian GP recap

This past weekend, the WPF hosted round 4 of the 2019 Puzzle Grand Prix, with puzzles by Russian authors. Puzzles/solutions/results are currently available under the previous link but should show up in the archive eventually. I’ll go over how it went for me below. One very interesting new variant on the test was “unequal lengths slitherlink”; here’s one:

Unequal-lengths slitherlink

[applet without answer check]

Rules Solve as a regular slitherlink. In addition, any two connected straight line segments must have different lengths.

I attempted to record myself solving again, video here. Unfortunately, I once again managed to hide half the puzzles, particularly my one mistake. Here’s my course through the contest:

2-3. Clouds (30 points in 4:48 for 6.3 points/minutes) and Clouds (46, 3:27, 13.4)

I started with the clouds because they came out of the printer soon and are a type that I’m reasonable comfortable with. I made a bit of a mess of the first one, which is typical for me at the start of a competition for me. By the second one I was warmed up (or got a bit lucky). I pretty much just drew the solution in there.

14-16. Doubleblock (30, 6:02, 5.0), Doubleblock (Variable) (80, 7:14, 11.1) and Doubleblock (Parquet, Liar) (57, 15:02, 3.8)

Next, I didn’t want to do the arithmetic squares, and had decided prior to the contest that I didn’t want to risk the 151 point arithmetical city. The doppelblock choice was rather arbitrary, it was what came up on top after flipping forward a few pages.

(Usually as a top 10 puzzler I’d expect I should have to try a big pointer like that, but I feel like the GP has consistently missed the goal having a couple of finishers this year. Judging by the huge total point value, I was hopeful to be able to fill the 90 minutes with more appealing puzzles.)

With the exception of the overvalued second puzzle, these went quite poorly for me. (Watching my recording of the second puzzle, I even wasted a lot of time there missing an easy deduction in the top rows.) I don’t think anything went wrong in particular with the first puzzle.

On the third, with a rather inelegant rule set (intended to arrange the possible clue values cyclically), I could have been better prepared; it took me a while to realise that most large/small values still allowed deductions regardless of whether they were lying or not. I couldn’t break in without some casework, but eventually I seemed to be on the right track. There was a scary moment close to the end where I’d made a bad deduction and I was close to having to erase the whole puzzle; thankfully I was able to take a step back and correct my error.

17. Slalom (64, 3:34, 17.9)

It seems the GP test solvers are not very familiar with the type. Of those 3:34, I spent 41 seconds carefully entering the solution code – those NZs are quite confusing. It was a pleasant clean solve, though watching the recording is slightly maddening, what with me ignoring obvious deductions all over the place.

18. Yagit (50, 3:49, 13.1)

I really enjoyed this one. I’m a bit familiar with the type, but still charged right in with wrong deductions. Once I saw how the puzzle worked it came out very nicely.

10-11. Slitherlink (Unequal Lengths) (39, 3:35, 10.9) and Slitherlink (Unequal Lengths) (62, 4:44, 13.)

After the Yagit I briefly looked at the Arithmetical City to see if it seemed approachable. However I was mostly irritated that the intruction booklet featured unused extra rules, and paged back to the type I was most looking forward to. The “unequal lengths” rule is a wonderfully simple variant rule that changes the type quite significantly.

My solves here were not particularly clean, but fast enough, particularly on the second puzzle.

8-9. Skyscrapers (20, 2:31, 8.0) and Skyscrapers (23, 3:04, 7.5)

Next I went for the skyscrapers. It’s not particularly strong for me as a latin square type, but as a German I’m well practiced… Neither solve was particularly clean, each time ending up with some quarter of the grid empty without obvious logical progress. I got the first one out well enough, but on the second I had already made a bad deduction before guessing, and ended up turning in an (obviously) broken solution.

Looking at the solve in retrospect, I wonder if I should go to more effort to catch errors like this. (Placing two 1s directly above each other seems like something that could be noticed without wasting too much time, but who knows?)

12-13. Striped Snake (59, 9:35, 6.2) and Striped Snake (78, 8:24, 9.3)

For the first of the snakes, I found the right place to start, but it took me quite a while to figure out that there were options for the bottom of the grid that looked different than what I started with. The second one was a pretty satisfying mix of experimentation and logic.

6.-7. Four Winds (20, 2:53, 7.0) and Four Winds (56, 8:36, 6.5)

At this point I had the two Four Winds left, and still a decent amount of time on the clock. Neither of the two felt like a particularly fast solve; particularly on the second I felt that I was scanning the grid for spots to make progress quite a bit, which is usually not something I’m fast at. Judging by the points per minute, it seems I did ok though.

The end

By the time I was done, I was down to about a minute. I gave the first puzzle a guessy try that didn’t work out. It might have been a better idea to double check, but chances would have been slim to fix anything in the time left.

Overall, a pretty good result for me, with 6th place after last month’s 5th. After a lousy first GP and missing the second GP as an author, it looks like I might end up in the top 10 again after all if I keep up this level.

Congratulations to the winner Hideaki Jo, and the whole Japanese team that dominated the round. You can see Yuki Kawabe’s writeup here, who solved the same puzzles 5 minutes faster and with one less mistake.

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