2021 WPF Sudoku and Puzzle GPs

Information and discussion on Puzzle Competitions
detuned
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Re: 2021 WPF Sudoku and Puzzle GPs

Post by detuned » Mon 01 Feb, 2021 11:03 pm

Sometimes the results can be very slow to materialise. I used to be the sudoku GP director and I still don’t fully understand why!

It’s fine to post after the test is over :)

detuned
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Re: 2021 WPF Sudoku and Puzzle GPs

Post by detuned » Mon 01 Feb, 2021 11:46 pm

Still some very strong results for the UK on round 1 as per the updated preliminary results! Four of us in the top 20 matches Japan, and is as much as Germany and USA combined :shock: 8-)

3. Freddie Hand 752
9. James McGowan 685
19. Neil Zussman 577

... and it seems a bit churlish not to give Sam an honorary mention in addition to the top 3 as well :)

20. Sam Cappleman-Lynes 571

EDIT: Results have been updated somewhat. It's kind of disappointing they aren't paying much attention to the answer keys behind the scenes. From what I recall I used to have to fill in a very messy spreadsheet, which I assume then formed part of a manual process with the website.

Puzzle_Maestro
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Re: 2021 WPF Sudoku and Puzzle GPs

Post by Puzzle_Maestro » Tue 02 Feb, 2021 12:00 am

Thanks Tom. I suspect my lead will be short-lived (since Yanzhe was penalized for inputting the codes for 4 and 5 in the *right* order) but hoping to hang on to second.

A strong showing for the UK indeed! We may be brought back down to earth by the subsequent non-numbers heavy round, but hopefully that won’t be the case!

kiwijam
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Re: 2021 WPF Sudoku and Puzzle GPs

Post by kiwijam » Tue 02 Feb, 2021 4:48 am

I also 'did a Yanzhe', so hoping to rise 5 places more.
Great start to 2021 Freddie!

pinkagape
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Re: 2021 WPF Sudoku and Puzzle GPs

Post by pinkagape » Tue 02 Feb, 2021 5:24 am

Well done everyone!

I had the anglers cave but didn’t read the key correctly, frustratingly.

When do they put the amendments through? I don’t want to have to do and redo the UK Puzzle League standings if there’s going to be turbulence.

Also, how are you supposed to do darts? I can’t find a technique at all.

Puzzle_Maestro
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Re: 2021 WPF Sudoku and Puzzle GPs

Post by Puzzle_Maestro » Tue 02 Feb, 2021 8:16 am

I think it’s probably best to wait for official results to be published before updating the league table. Should be released by next Monday.

detuned
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Re: 2021 WPF Sudoku and Puzzle GPs

Post by detuned » Tue 02 Feb, 2021 8:54 am

I thought it was all official by Wednesday, but that might easily have changed since my time.

I would also love to hear more re darts - as far as I can see it’s along the lines of get lucky with a semi-educated guess.

I wrote a gimmicky darts puzzle once, but I don’t think the trick here (or even any attempt to generalise) is particularly useful. The gimmick was more there to help me as the author to prove uniqueness without needing to do any programming.

https://tcollyer.blogspot.com/2016/02/f ... break.html

detuned
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Re: 2021 WPF Sudoku and Puzzle GPs

Post by detuned » Tue 02 Feb, 2021 8:59 am

Any protests or amendments should be directed to puzzlegp@worldpuzzle.org by 23:59 (GMT + 1) on Wednesday February 3rd. Protests after this deadline will not be considered, and official results will then be published. These results will be final.
Well they haven’t updated my text at any rate - I haven’t paid attention to how rigidly they stick to this :) seems like results will be ready by Thursday then

Puzzle_Maestro
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Re: 2021 WPF Sudoku and Puzzle GPs

Post by Puzzle_Maestro » Tue 02 Feb, 2021 9:30 am

They’re pretty inconsistent with publishing official results; sometimes they’re published by Thursday but one time they were still preliminary after two weeks!

Darts is mostly just educated guessing, as Tom says. You can use certain observations to narrow down the search space (bounding, parity, etc) though! Another ‘strategy’ - which worked well for the right puzzle, not so much for the left - is subtracting the largest numbers from the total (i.e we have one of 1274, 1266 or 1240) reducing this puzzle to three darts (though you do now have 3 numbers to work with).

For the left puzzle it helped to combine this with a bit of parity; we need either 1 odd or 3 odd, so 1420 was immediately out of the question, and having neither of 966 or 753 is also easier to rule out. There are other potential methods but I suspect they would be slower than straight guessing or casework.

Feadoor
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Re: 2021 WPF Sudoku and Puzzle GPs

Post by Feadoor » Tue 02 Feb, 2021 3:17 pm

There's been an update to the results to reflect the issue with puzzles 4/5. James climbs a few places and Freddie slips into 3rd and will have to wait a little longer for an individual victory.

3. Freddie Hand 752
9. James McGowan 685
19. Neil Zussman 577

jupilogy
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Re: 2021 WPF Sudoku and Puzzle GPs

Post by jupilogy » Tue 02 Feb, 2021 6:09 pm

Ah, Freddie was so close to second as well!

Nilz
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Re: 2021 WPF Sudoku and Puzzle GPs

Post by Nilz » Tue 02 Feb, 2021 6:30 pm

I really enjoyed this test, even if I did spend way too long factorising large numbers :roll: Some really nice underrepresented puzzle types (I'm thinking mainly of the football puzzle), and it's nice to see a strong UK showing. :)
Can we claim that makes us the best 'natural' team in the world, while everyone else is only good at puzzle types they've seen a million times before? Probably not. :D
I intended to solve the Darts puzzles in my head while the rest was printing, but gave up on that idea very quickly and never came back to them, and so it's only this discussion that's alerted me to the 4/5 issue. Good job the puzzles themselves seem to have been checked more thoroughly!

El Loco
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Re: 2021 WPF Sudoku and Puzzle GPs

Post by El Loco » Tue 02 Feb, 2021 8:33 pm

I enjoyed my first try at a World Puzzle GP on a last minute impulse decision, though my experience should be educational to other newcomers:

1) Check your printer is working & has ink in before you start.
- Schoolboy error. :roll: 10 minutes wasted looking for an ink cartridge (unsuccessfully).
2) As others note, have an idea of which puzzles you'll go for first.
- I was just going through in sequence skipping anything that looked lengthy/if I got stuck early on.
So Q1 bypassed (not sure how to attack something that large :shock:) . Q2 Football worked out, not realising it wasn't easy providing the long answer key without the grid printed out. A simple error lost me the points. :(
3) Probably have a quick look through the whole paper at the start
- Got lucky. Realising how difficult some puzzles would be without the grids to write on (note - improve IT skills/have squared paper) I looked for the more manageable puzzles. Ended up doing the Prime Paths puzzles, which were the last 2 questions and scored good points. :D
4) Watch the time
- I earmarked some hopefully quicker puzzles for the end, but not much good if the time expires when you're entering the key. :roll:
5) Take advantage of the hints and wisdom on UKPA
- Now I know it's here!

puzzlemad
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Re: 2021 WPF Sudoku and Puzzle GPs

Post by puzzlemad » Wed 03 Feb, 2021 11:27 pm

Well done everyone - in particular Freddie - that's fantastic.

As for me - less said the better - wasted silly points and time with the scrabble and anglers cave - got virtually to the end of the scrabble and couldn't finish it off and had done something wrong with the anglers - only got one of the set yet to fully solve. Is there a way to get into puzzle 1 - I've not had a massive look at it yet.

Darts - we had those back in 2005 as the weakest link round. Quite a few of us were still sat our tables without moving to the team one at the end with those. I'd not taken any scrap paper to write on so that didn't help. I've seen them occasionally since.

Feadoor
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Re: 2021 WPF Sudoku and Puzzle GPs

Post by Feadoor » Thu 04 Feb, 2021 8:16 am

puzzlemad wrote:
Wed 03 Feb, 2021 11:27 pm
Is there a way to get into puzzle 1 - I've not had a massive look at it yet.
I solved it after time. My way into it was to subtract away cunningly-chosen disjoint clumps of areas from the entire total to leave behind only two region. Doing that in a few different ways gave me enough pairs with appropriately extreme sums to crack the whole thing open.

kiwijam
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Re: 2021 WPF Sudoku and Puzzle GPs

Post by kiwijam » Fri 05 Feb, 2021 2:58 am

Yes. To elaborate:
e.g. Look at the 32, 38, and 39 regions. They sum to 109, the whole puzzle sums to 136, so the left most pair of regions sum to 27.
Now look at the 47. The left 2 are 27, so the right 2 are 20.
This can continue along the lower edge. You'll find that the 50 and 37 sum to 30, so must be 14+16.
And now that original leftmost pair must be 15+12.
Some more playing in the bottom-right area leads you to your first known values.

puzzlemad
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Re: 2021 WPF Sudoku and Puzzle GPs

Post by puzzlemad » Sat 06 Feb, 2021 8:48 am

Thanks James and Sam. I have solved it (my way) but will have another look with these hints to doing it.

Puzzle_Maestro
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Re: 2021 WPF Sudoku and Puzzle GPs

Post by Puzzle_Maestro » Tue 16 Feb, 2021 7:45 am

Preliminary results for round 2 of the sudoku GP:

38. Freddie Hand 482
41. Sam Cappleman-Lynes 481
78. Tom Collyer 372

Tantan and Tiit well clear of the field, as well as Tomasz Skrzypczak (their first appearance in the top 3, I believe?).

That was a fairly bumpy round for me so somewhat surprised with the result; for several minutes I insisted that the top left 18 cage of the killer hidden arrows contained 13 in the arrowhead, and chased a couple of pointless bifurcations in the cloned shapes sudoku, among others.

detuned
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Re: 2021 WPF Sudoku and Puzzle GPs

Post by detuned » Tue 16 Feb, 2021 9:26 am

Oh that’s frustrating, I forgot to answer Rossini, and did something silly with Renban. Bye bye 130 odd points :/
FB51CCE6-E5A3-4666-A773-478B3F0D6175.png
FB51CCE6-E5A3-4666-A773-478B3F0D6175.png (603.19 KiB) Viewed 818 times
Killer-arrows is a poorly designed variant that requires you to figure out the “trick”. All the cages are forced instantly: for a >= 4 cell cage total X, with corresponding 2 digit arrow AB you get the relationship X = 11A + 2B, which gives you a very limited list of possibilities for X. 18 is not one of them so you know it’s a 9 with 3 others summing to 9.

I had the forethought to make a list of the possibilities beforehand - I was meaning to share on this forum as a protest against gimmicky variant design but in the end I forgot (im probably still suffering a bit from the killer marathon!)

The puzzle itself wasn’t particular nice after resolving the cages, very fiddly sudoku logic to finish it

detuned
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Re: 2021 WPF Sudoku and Puzzle GPs

Post by detuned » Tue 16 Feb, 2021 9:31 am

Oh and if I’m not wrong classic 6 required a y-wing... if so it seems the policy to not have harder techniques unless very well signposted has gone out the window.

I enjoyed the renban and cloned shapes - not exactly smooth solving, but definitely satisfying!

Feadoor
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Re: 2021 WPF Sudoku and Puzzle GPs

Post by Feadoor » Tue 16 Feb, 2021 10:36 am

Yes, Classic 6 needed either advanced techniques or a well-chosen *ahem* bifurcation *ahem*. I don't 100% agree that Killer Arrows is just a gimmick - the fact that the arrow sum is forced for any given cage total doesn't necessarily make it a bad variant for me. But I don't think it was showcased particularly well here, and agree with the "fiddly" assessment of the contest puzzle.

Renban was a disaster solve for me (I was able to nonetheless appreciate the logic) but Cloned Shapes went very smoothly. My biggest gripe is with the Irregular No Touch Skyscraper Sudoku which combined three perfectly cromulent variants into a single hybrid and didn't do so in a very compelling way. The puzzle just felt easy and overclued.

jupilogy
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Re: 2021 WPF Sudoku and Puzzle GPs

Post by jupilogy » Sat 20 Feb, 2021 10:34 am

Puzzle round 2 instruction booklet is out!

Some of these look tricky. I’m worried about making a mistake on 12 (BACA) and 20 (coupled tapa). Like maybe I’ll forget that the lettered cells in BACA can be crossed out, or I’ll fill in the wrong cell on tapa. :shock:

I think I’ll put a square around the ‘good’ cells in BACA so I don’t get mixed up. As for tapa, I guess I just need to be careful.

Feadoor
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Re: 2021 WPF Sudoku and Puzzle GPs

Post by Feadoor » Sat 20 Feb, 2021 10:50 am

Note that this is version 2 of the IB; the difference from version 1 is that three puzzles worth 150+ points have been removed and the total points reduced from nearly 1300 to a "mere" 841 :D

jupilogy
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Re: 2021 WPF Sudoku and Puzzle GPs

Post by jupilogy » Sat 20 Feb, 2021 10:59 am

Yikes! I wonder if they’ll release those extra puzzles after the competition. Or if those puzzles actually exist.

detuned
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Re: 2021 WPF Sudoku and Puzzle GPs

Post by detuned » Tue 02 Mar, 2021 7:50 pm

Seems no-one here remembered to post that it was a puzzle GP round this weekend. A nice mix of puzzles I thought, even if the Valentine's theme was a couple of weeks too late.

Still, it was not a bad UK showing: 32 + James by my count. Aside of the usual suspects at the top of the leaderboard, really nice to see a strong showing from Dylan Gibbs and Matthew White.

Top 3 UK:

15 James McGowan 705
27 Neil Zussman 621
37 Freddie Hand 556

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