While the IB is being published I thought I would provide a few practice links on the puzzles included in this round.

Shading
Water Fun (aka Aquarium) - You can find lots of practice puzzles here: http://puzzlepicnic.com/genre?waterfun
Nurikabe - http://nikoli.com/en/puzzles/nurikabe/
Shakashaka - http://nikoli.com/en/puzzles/shakashaka/

Nurikabe Loop - This is an exploratory type, with rules slightly different from the original puzzle from Akil Oyunlari as this puzzle follows the 2X2 rule of Nurikabe for the loop. I have posted one example puzzle here : https://logic-masters.de/Raetselportal/Raetsel/zeigen.php?id=0002YV

Loops
Simple Loop - Two practice puzzles should suffice: https://nbpuzzles.wordpress.com/simple-loop/ http://ravimacherla.blogspot.com/2014/05/puzzle-no13-simple-loop.ht...
Straight Loop - You can find some practice puzzles here : https://logic-masters.de/Raetselportal/Suche/erweitert.php?tag=Gerad...
Cross Loop - Some pratice puzzles here: https://logic-masters.de/Raetselportal/Suche/erweitert.php?tag=Achte...

Simple Loop with Shading - Don't have any practice puzzles available, but Yajilin practice would help for this one: http://nikoli.com/en/puzzles/yajilin/

Also adding one of the rejected puzzles from the set as practice. Any guesses on the (hidden) theme?

Shakashaka






Attachments
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Shakashaka.PNG (17KB - 6 downloads)

There are two rule alternatives for Water Fun / Aquarium puzzles.
The difference is if unconnected sections of water in the same region must have the same height.
e.g. In your example, you use the logic that: R2C4 is filled means that R2C2 is filled. (Some puzzles don't do this.)
But I don't think of this as a connected area of filled cells, unless you mean area is "the region, with thick edge". So an area is always connected?
Perhaps this sentence is confusing: "Connected areas of filled cells must have same surface height everywhere" should be meaning: "Filled cells in an area must have same surface height everywhere".

Maybe I can say that better: Puzzle Picnic (where you copied your rules from, and suggest people practice) uses the opposite rule from your example. (e.g. Reveal the answer to http://puzzlepicnic.com/puzzle?4999)
Which rule is correct, or will it not matter?

Edited by kiwijam 2019-02-22 9:03 AM

Yes you are right there is always some confusion about the rules for these puzzles so we deliberately included that in the example and thanks for catching it.

The "Connected areas of filled cells must have same surface height everywhere" does mean "Filled cells in an area must have same surface height everywhere"

Hope this clarifies

(For Water Fun,) is it right to say that, for each region, you can draw some horizontal line such that the part of the region below the line is all filled, and the part of the region above the line is all unfilled?

Yes, but remember, that line can be on the border as well. That is either entire region is full or empty.

The test has started.

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?	Straight Loop
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

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?	Shakashaka
What was your opinion about the answer key extraction?	Answer keys were horrible
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

Solving was fun and went smoothly, but I struggled way too much with the answer keys. I tend to confuse 'length of loop segment' with 'number of cells'. On top of that, this time I also put the right answer in the wrong box multiple times. :-(

Most of the submission errors were actual errors (except for the "right answer in the wrong box" cases). And in one case, both "length of loop segment" and "number of cells" are used in the same answer key. If any one notation ("length of loop segment" or "number of cells") is consistently used, points will be awarded.

I disagree, in an upside down U, you should be able to fill out both legs independently, according to the stated rules (and how I know "Water Fun", contrasted with the croco Aquarium which use mstang's suggested rule).

This was a lot of fun, thank you Amit. That third Straight Loop sure threw me for a loop!

Also the big Nurikabe Loop fell very easily, but I probably got a little lucky there.

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?	SL with Shading
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 think the Water Funs give the same unique answer with either rule, so it didn't matter much.
I struggled with the last Straight Loop until I realised I was using Balance Loop logic instead (oops), they start the same way but in this case the lengths don't matter if the loop doesn't turn at the circle.
The middle Cross Loop was a favourite.

Great quality puzzles, thanks Amit!

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?	Nurikabe
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

I had little trouble entering keys for Cross Loop. Great contest besides that!
By the way, please update PR & SM ratings

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?	Cross Loop
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

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?	Nurikabe Loop
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

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?	Cross Loop
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

What was your opinion of the distribution of easy/hard puzzles?	Too many hard puzzles
What did you think about the puzzle quality of the test?	Fairly Nice
Which set of puzzles did you like the most?	Straight Loop
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?	I have a different complaint

Its interesting you mention that, because Rakesh also had a similar feedback while test solving where he compared it to the Balance Loop logic.

I am glad to hear this feedback. The straight loop type was selected after seeing the puzzles you had posted on the Logic Masters portal.



This one was difficult to allocate points. Once the center was resolved the rest of the puzzle gets resolved quickly.

We had discussed the answer key for this puzzle type and were not completely satisfied with the diagonal answer keys but decided to keep it as a compromise.
It is a difficult puzzle type to set a nice answer key for.
The Logic Masters portal where I cam across this type uses locations of crossings, which is a good answer key but would have been terrible for the second puzzle which had a very large number of crossings.

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?	Nurikabe Loop
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

My favorite PR round in a long time. Very nice and interesting puzzles, and solveable enough that I actually had enough time to at least look at them all (I just am not that fast and accept that). I need to figure out some theorems for straight loop; I couldn't get anywhere with those.

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?	Water Fun
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