UKPA Masyu Contest 14 May - 19 May 2021

Information and discussion on Puzzle Competitions
Post Reply
david mcneill
Posts: 461
Joined: Mon 21 Jun, 2010 2:02 pm

UKPA Masyu Contest 14 May - 19 May 2021

Post by david mcneill » Wed 05 May, 2021 7:22 am

This is the discussion thread for the upcoming UKPA Masyu Contest. UK and international competitors are welcome.

Dates: Friday 14 May 2021 - Monday 17 May 2021
Duration: 90 minutes
Puzzles: 15 puzzles, including 4 standard Masyu, 1 large Masyu and 2 each of 5 Masyu variants
Instruction booklet: posted at https://ukpuzzles.org/contests.php?contestid=62

Feadoor
Posts: 253
Joined: Thu 17 May, 2018 7:08 am

Re: UKPA Masyu Contest 14 May - 17 May 2021

Post by Feadoor » Thu 06 May, 2021 8:11 pm

Thanks, David!

Can I confirm that the constraint in No Touch Masyu is only on orthogonally adjacent cells? When I see the phrase "No Touch" in other contexts (for example No Touch Sudoku) it brings to mind a constraint that also includes diagonal touching, so just making sure that isn't the case here.

david mcneill
Posts: 461
Joined: Mon 21 Jun, 2010 2:02 pm

Re: UKPA Masyu Contest 14 May - 17 May 2021

Post by david mcneill » Fri 07 May, 2021 10:10 am

Sam,

Thanks for the question. The constraint in No Touch Masyu only applies to orthogonally adjacent cells. Unvisited cells are allowed to be diagonally adjacent. I had seen the name previously applied to puzzles with the same rule set. Hope there's no confusion.

David.

eratosthenes
Posts: 13
Joined: Fri 12 Jun, 2020 5:22 pm

Re: UKPA Masyu Contest 14 May - 17 May 2021

Post by eratosthenes » Fri 07 May, 2021 11:02 am

For the Deformable Masyu, I'm having trouble working out how to approach the puzzle. Is it a case of just testing each white circle to see whether changing it to black causes a contradiction?

Puzzle_Maestro
Posts: 120
Joined: Mon 11 Mar, 2019 5:23 pm

Re: UKPA Masyu Contest 14 May - 17 May 2021

Post by Puzzle_Maestro » Fri 07 May, 2021 11:59 am

That is a valid method of solving, but it may not be the most fun. An important pattern to be aware of here is the 'horseshoe' as I call it; if we have a U formed by three segments of length 2, there cannot be a circle in the gap. Note that R6C3 being white forces this pattern above. There is another (slightly trickier) application of this idea immediately after and then the puzzle breaks apart.

eratosthenes
Posts: 13
Joined: Fri 12 Jun, 2020 5:22 pm

Re: UKPA Masyu Contest 14 May - 17 May 2021

Post by eratosthenes » Sun 09 May, 2021 5:19 pm

Thanks, I see it now. Definitely the hardest of the variants to get my head around!

detuned
Posts: 2097
Joined: Mon 21 Jun, 2010 2:25 pm
Location: London, UK
Contact:

Re: UKPA Masyu Contest 14 May - 17 May 2021

Post by detuned » Sat 15 May, 2021 11:11 am

I have seen a certain amount of (unhelpful) online chatter on discord servers: namely Cracking the Cryptic (which I have now left) and Puzzler’s Club.

Yes, we are aware there is a problem with new registrations at this moment in time. And yes, we are also aware there’s a problem with old accounts that have previously been deactivated. We are trying to fix this as best we can, but also please be aware there are some circumstances that are limiting exactly what we can do about this currently. Please bear with us and apologies in advance to those of you who are currently unable to competitively take part in this contest!

gareth
Posts: 1301
Joined: Thu 24 Jun, 2010 9:27 pm
Contact:

Re: UKPA Masyu Contest 14 May - 17 May 2021

Post by gareth » Sat 15 May, 2021 11:35 pm

Registration is now working again.

Sorry for the problems registering over the past few weeks.

david mcneill
Posts: 461
Joined: Mon 21 Jun, 2010 2:02 pm

Re: UKPA Masyu Contest 14 May - 17 May 2021

Post by david mcneill » Sun 16 May, 2021 11:52 am

Having become aware that some puzzlers have been having difficulty registering, I have extended the competition deadline by 48 hours. This means that solutions must be submitted no later than 11pm BST on Wednesday 19 May. The results of the competition will be published at 2pm on Thursday 20 May. I am really sorry that fans of puzzling online have been affected in this way. I hope that those who have already competed won't mind the extra wait.

Thank you,

David.

Feadoor
Posts: 253
Joined: Thu 17 May, 2018 7:08 am

Re: UKPA Masyu Contest 14 May - 19 May 2021

Post by Feadoor » Tue 18 May, 2021 8:27 pm

Thank you for the contest, David! I was beset by printer issues but was able to take part anyway using good old Snipping Tool. Always a pleasure to solve your puzzles.

david mcneill
Posts: 461
Joined: Mon 21 Jun, 2010 2:02 pm

Re: UKPA Masyu Contest 14 May - 19 May 2021

Post by david mcneill » Thu 20 May, 2021 1:22 pm

My first attempt to set a Masyu contest. Delighted so many took part. Just over 100 competitors, of whom 42 got all the puzzles correct within the time. I was nervous beforehand about possible answer key errors and there were no fewer than 17 puzzlers who submitted answers for all 15 puzzles but made a single error.

The top 3 put in exceptional performances. Congratulations to Endo Ken (Japan), Walker Anderson (USA) and Freddie Hand (UK). Next best UK-registered puzzlers were William Hu and Neil Zussman.

Look out for more competitions on the website. Don't know what I'll do next.

Feadoor
Posts: 253
Joined: Thu 17 May, 2018 7:08 am

Re: UKPA Masyu Contest 14 May - 19 May 2021

Post by Feadoor » Thu 20 May, 2021 1:32 pm

Thanks David! The puzzles were fantastic :)

I failed to check my printer beforehand and after finally convincing it to join my home network I found that it was actually out of ink (!), so I ended up solving under less-than-ideal circumstances. I really struggled with counting the answer keys on my screen so I wasn't surprised to see multiple errors on my part.

My favourite puzzles were Unequal Lengths 2, No Touch 2 and Two Loops 2, but all of the puzzles were really fun to solve.

cmusson32
Posts: 2
Joined: Thu 15 Nov, 2018 2:21 pm
Location: Loughborough

Re: UKPA Masyu Contest 14 May - 19 May 2021

Post by cmusson32 » Thu 20 May, 2021 2:08 pm

Thanks David, really enjoyed the contest!

I'm delighted with my final placement. I never expected to get to finish all 15 puzzles so I couldn't quite believe it when I didn't hit any major roadblocks. The trickiest puzzle for me was Two Loops 2, but maybe I can put that down to not expecting to make it that far and so not having practised any puzzles of that type :lol:

detuned
Posts: 2097
Joined: Mon 21 Jun, 2010 2:25 pm
Location: London, UK
Contact:

Re: UKPA Masyu Contest 14 May - 19 May 2021

Post by detuned » Thu 20 May, 2021 2:34 pm

david mcneill wrote:
Thu 20 May, 2021 1:22 pm
My first attempt to set a Masyu contest. Delighted so many took part. Just over 100 competitors, of whom 42 got all the puzzles correct within the time. I was nervous beforehand about possible answer key errors and there were no fewer than 17 puzzlers who submitted answers for all 15 puzzles but made a single error.
Answer keys for loop puzzles are hard to get right, particularly under time pressure! It’s worth bearing in mind that of those 17 I’d expect some to have been genuine errors rather than typos. Then again, if you were to get the puzzle GP data and check the proportion of people who submitted n answers and n were correct I doubt it’s too far off this (I’d bet it’s probably worse if anything) - perhaps it seems more prominent for this contest because lots of people were well under the time limit.

I spent a decent amount of time checking my keys, but I still had one that slipped through. It happens, and I suppose the main thing is that plenty of other people managed the keys just fine whilst still solving like the clappers!

puzzlemad
Posts: 955
Joined: Mon 21 Jun, 2010 10:20 pm
Location: Oldham

Re: UKPA Masyu Contest 14 May - 19 May 2021

Post by puzzlemad » Thu 20 May, 2021 3:29 pm

Thanks David for a great competition It was good to be able to solve all successfully in the time (pity I was careless with a couple of the answer keys - one being the 75 pointer!) I'd corrected one error in that but missed the other.

emma
Posts: 328
Joined: Wed 22 Jun, 2011 4:58 pm

Re: UKPA Masyu Contest 14 May - 19 May 2021

Post by emma » Thu 20 May, 2021 4:36 pm

I've never had time left for thorough checking before - it paid off, because I found about four errors (and ended up being the slowest of the people who didn't make any mistakes).
I didn't like the deformable example, so I wasn't planning on doing those, until I realised that I'd done almost everything else.

Puzzle_Maestro
Posts: 120
Joined: Mon 11 Mar, 2019 5:23 pm

Re: UKPA Masyu Contest 14 May - 19 May 2021

Post by Puzzle_Maestro » Thu 20 May, 2021 5:23 pm

Perhaps a small point of interest: the rankings at the top are very similar to those of PR round 2 (loops). Namely, the contestants in positions 1,2,3,4,6,8,10,12 in this contest are roughly around the same position in both contests. I don't think I've seen such similarity between two contests before!

Post Reply