What was your opinion of the distribution of easy/hard puzzles?	Just right
What did you think about the puzzle quality of the test?	Very nice
Which set of puzzles did you like the most?	Curve Data
What was your opinion about the answer key extraction?	Perfect answer keys
Of the puzzles you solved/attempted, how well did the point values reflect the difficulty?	Most puzzles were worth the right amount
What was your opinion of the booklet formatting and printing?	Just right

Overall a very nice test. The theming is excellent (although it's questionable that the curve data has "easy" worth 5 points and "medium" worth 4 points...) and the puzzles themselves were mostly nice.

Matchsticks is a very weird genre, and I'm not sure it's logical. I'm sure most of the penalties by people are in this genre. One good thing about commonly encountered puzzles (Nikoli-style etc) is that you can verify your answer easily; here, verifying your answer to Matchsticks requires you to practically solve the whole thing again. (All optimization puzzles fall in this bucket too.) Not that it's a bad idea to include them, but you need to be really careful with how you do it. I'd say Matchsticks 2 is the most difficult puzzle in the test; Matchsticks 3 is in fact fairly easy (you have enough room to make practically any number you want, so getting a proof is really quick).

Some minor quibbles: Easy as Snake doesn't need the word separation (spaces are irrelevant for the puzzle), but it's fine. For Word Division, with how many native English words are used, I largely intuited the solves by trying to read some reasonable words I can see from the board; people not used to English won't be able to do this.

Double Cross turned out to be particularly enjoyable, compared to my first reaction of "huh, won't this be really trivial?"

Edited by chaotic_iak 2020-05-25 11:42 PM

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Edited by kiwijam 2020-05-26 6:22 AM

Well that wasn't true.
The solution to #3 requires moving 4 matchsticks, not 7, and is therefore invalid according to your statement!

I spotted the 'obvious' answer (smallest number using 23 matchsticks) immediately, then spent a long time looking for larger numbers that needed more moves.
At least with instant grading I eventually gave up and put it in just in case I could move on.

There is a solution that gives the same number that moves exactly 7 matchsticks. It leaves a gap between some digits.

What was your opinion of the distribution of easy/hard puzzles?	Just right
What did you think about the puzzle quality of the test?	Very nice
Which set of puzzles did you like the most?	Word Nurikabe
What was your opinion about the answer key extraction?	Perfect answer keys
Of the puzzles you solved/attempted, how well did the point values reflect the difficulty?	Most puzzles were worth the right amount
What was your opinion of the booklet formatting and printing?	Just right

Thanks Amit for this enjoyable set! Word puzzles were very nice. In casuals, I did a blunder in mastermind 3 and lost a lot of time. My favorites puzzles were: word nurikabe and curve data.

What was your opinion of the distribution of easy/hard puzzles?	Just right
What did you think about the puzzle quality of the test?	Fairly Nice
Which set of puzzles did you like the most?	Word Division
What was your opinion about the answer key extraction?	Mostly perfect answer keys
Of the puzzles you solved/attempted, how well did the point values reflect the difficulty?	Most puzzles were worth the right amount
What was your opinion of the booklet formatting and printing?	Just right

You could reach the answer with 7 moves (or any n really) if some moves were transpositions. (Ie. Keep moving the D around until you have 4 moves left). I agree that it's a questionable inclusion.
A possible improvement would be making sure that the solution is reached by the minimum number of moves.

Thanks Kishore.
I hope you are encouraged to solve more of these puzzle types in the future.

What was your opinion of the distribution of easy/hard puzzles?	Too many medium difficult puzzles
What did you think about the puzzle quality of the test?	Very nice
Which set of puzzles did you like the most?	Word Division
What was your opinion about the answer key extraction?	Perfect answer keys
Of the puzzles you solved/attempted, how well did the point values reflect the difficulty?	Most puzzles were worth the right amount
What was your opinion of the booklet formatting and printing?	Just right

Thank you so much for this wonderful set, Amit!
I was dreading the casual and word round since the week where that I missed the object placement round, and realised that this round will be crucial to getting that 4/6 round base points. I was aiming to score about 30, so I am quite happy with the number of puzzles I could logically solve!

Absolutely loved the Easy, Medium Hard themeing, the cute easter egg answer key on the last puzzle, and the word puzzles were all very logical and enjoyable!

I think I spent a LOT of time trying to figure out puzzle 6 (mastermind), and I don't think I understand i even now :P, but other than that it was smooth sailing for me.
Loved the round!

What was your opinion of the distribution of easy/hard puzzles?	Just right
What did you think about the puzzle quality of the test?	Very nice
Which set of puzzles did you like the most?	Word Division
What was your opinion about the answer key extraction?	Answer keys could have been better
Of the puzzles you solved/attempted, how well did the point values reflect the difficulty?	Most puzzles were worth the right amount
What was your opinion of the booklet formatting and printing?	Just right

Thanks Ivan.
It was my first attempt at creating curve data puzzles. I will need a lot more experience before I can have sufficient expertise over adusting the level of difficulty for curve data. In fact both of the original puzzles submitted for EASY and MEDIUM turned out to be non-unique. But thanks to Rakesh's diligent testing I was able to fix it before the test.


I completely understanding the feeling you describe where the solver is not sure if the answer is correct or not. However within optimization problems too there are several types of problems and I tried to present it as close to a constrain optimization problem as possible.
I think optimization puzzles should also have some representation. We had an entire round of these in WPC 2017.



This is a good point that you bring up about the Word Division puzzles. I was thinking about using foreign language words (words for Easy, Medium, Hard in different languages). But that theme was already used in the Mastermind puzzles, so eventually I went with synonyms within English.

Thanks Harmeet

After reading the discussion regarding the Matchsticks puzzle I think I missed a couple of aspects during the test.
I think the rule that each matchstick can be moved exactly once needs to be specified explicitly. Otherwise with transpositions you are right that the target can be achieved in any number of moves.
I had a specific solution in mind which like Ivan pointed out can be achieved in exactly seven moves.

In hindsight there is also room for improvement of the answer key which should possibly be asking for information about which matchsticks are being moved and to which location.

Without this kind of answer key and the explicit rule to restrict transposition I agree with your recommendation about asking for a solution which is reached by the minimum number of moves.

Thanks Priyam.

What was your opinion of the distribution of easy/hard puzzles?	Just right
What did you think about the puzzle quality of the test?	Very nice
Which set of puzzles did you like the most?	Word Division
What was your opinion about the answer key extraction?	Perfect answer keys
Of the puzzles you solved/attempted, how well did the point values reflect the difficulty?	Most puzzles were worth the right amount
What was your opinion of the booklet formatting and printing?	Just right

I really enjoyed the word puzzles, those were the fun part of the contest. Also, the casual puzzles were fascinating because time taken to solve them was non-linear :D

Thanks to the 206 participants from 37 countries. Congratulations to Freddie Hand, Jeffrey Bardon and Endo Ken for taking the top 3 spots. Also congratulations to Michael Ley and James McGowan for completing the test error-free (without any submission errors). Choi Yong Seok (South Korea) was the first to take the test while Daniel Victor (India) was the last person to start the test. The median score of the test was 50.7.

Top results for countries with 10+ participants:

India (33): Prasanna Seshadri, Rohan Rao and Priyam Bhushan
Japan (23): Ryotaro Chiba, Taigo Ando, Kosei Yoshimori (ranks 2-4)
USA (20): Walker Anderson, Jenna Rivet and Todd Geldon (ranks 2-4)
France (11): Denis Auroux, Anne Limoges and Philippe Meyer
Poland (10): Tomasz Skalski, ralf09, Lukasz Kalinowski

Thanks Amit Sowani for the puzzles!

Participants may share feedback on the results page and rate the puzzles on the contest page.

Rohan Rao (18), Pinijpong (17), Yunguowoo (13) and Ashish Ghogre (13) led another leader-board in this test.

The Solution Booklet is now available here.

What was your opinion of the distribution of easy/hard puzzles?	Just right
What did you think about the puzzle quality of the test?	Very nice
Which set of puzzles did you like the most?	Word Division
What was your opinion about the answer key extraction?	Mostly perfect answer keys
Of the puzzles you solved/attempted, how well did the point values reflect the difficulty?	Most puzzles were worth the right amount
What was your opinion of the booklet formatting and printing?	Just right

Don't know about matchsticks - they kinda seemed like guesswork for me. Loved the word puzzles though.