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Logic Masters India announces October Puzzle Test 1 — Nikoli Selection

Date : 9^th and 10^th October

Puzzle Types : 15 Selected puzzle types from nikoli.com — 18 main puzzles + 3 Marathon puzzles

Author : Tom "detuned" Collyer

Length : 100 minutes

IB and Submission Link : http://logicmastersindia.com/M201010P1

Chinese translation of rules are available on http://www.sudokufans.org.cn/forums/index.php?showtopic=118

I am unable to understand the Hitori answer key with respect to the given example.

rakesh_rai - 2010-10-03 2:36 PM

I am unable to understand the Hitori answer key with respect to the given example.

answer key should be 21022. Updated in IB.

For LITS, does "consecutive" mean "connected" squares?
"Consecutive" normally means four squares through which a single continuous path can be drawn. In that case, we cannot make a T with consecutive squares.

Yes, it is "connected".

Is it possible to provide a link to a "real" Suraromu puzzle? I have never seen one of these before and do not subscribe to nikoli.

Thank you,

David McNeill.

Can we solve the three marathon puzzles before the 1st 18?

Yes you can, but it might be preferable to solve the 18 basic puzzles first to ensure a time bonus.

For the LITS puzzle, do we need to use all the pieces i.e L, I, T, S at least once?

It is not necessary to use all pieces. The rules do not require that.

Rohan Rao - 2010-10-04 9:28 PM

Can we solve the three marathon puzzles before the 1st 18?

As mentioned in the IB, The "point value" of a main puzzle > The "point value" of a marathon puzzle > The "point value" of time bonus
[ "Point Value" is points you get for spending a minute ]
To secure more points, you should be doing the main puzzles first.

For Numberlink, does every cell need to be filled? The rules currently do not say so, but it seems to be implied (indirectly) as the answer key has no mention of blank cells.

The IB mentions marathon puzzles as "...finest tradition of fold out Nikoli puzzles..." - What is meant by fold out puzzles? Does it mean large puzzles which exceed the regular page size?

rakesh_rai - 2010-10-05 2:13 PM
For Numberlink, does every cell need to be filled? The rules currently do not say so, but it seems to be implied (indirectly) as the answer key has no mention of blank cells.

Lets wait till Tom comments on this tomorrow. In the meantime I suggest take a look this wonderful analysis by Tom on using-all-cells-in-NumberLink
http://blogs.warwick.ac.uk/tcollyer/entry/friday_puzzles_71/

Also, the very very nice primer by mellowmelon on how to solve Numberlinks : http://mellowmelon.wordpress.com/2010/07/24/numberlink-primer/

rakesh_rai - 2010-10-05 2:13 PM
The IB mentions marathon puzzles as "...finest tradition of fold out Nikoli puzzles..." - What is meant by fold out puzzles? Does it mean large puzzles which exceed the regular page size?

I myself have never seen traditional "fold-out" Nikoli puzzles. I'll be surely interested in seeing one, if anyone can share.
But, yes, the "marathon" puzzles are little larger than the "main" puzzles :-)

Nikoli's main magazine is about 15cm by 25 cm which is good for having several "standard" puzzles on a page but not always for very large puzzles, so each one has a fold-out page with two extra large puzzles that is 30 cm by 25 cm. Nikoli puzzles come in certain standard sizes, so types like Masyu tend to be 10x10 or 18x10 or 17x17 in white cells. A fold-out puzzle is 64x50 typically, and takes at least an hour for the "expert time" (Nikoli puzzles come with time ratings sometimes).

I have a feeling these are not true fold-out puzzles, but are certainly very large. There is an intermediate size - what I'd call a "full-page" Nikoli puzzle - which are 31x45. A whole magazine, "Giants", has just full-page and fold-out puzzles and is my favorite thing to purchase since each puzzle is very carefully constructed but takes awhile to solve. Nikoli has also released 2 "poster" sized kakuro (124 x 90) and slitherlink (178 x 128), which are quite formidable challenges, probably taking at least a day if not a week to finish, considering possible mistakes. See here: Large Kakuro

Thanks Deb and MoTriS. The links on numberlink were quite a good read. Hopefully, it will help me (and many others) to solve the numberlink in the coming LMI puzzle test. Also, after looking at the picture of the kakuro poster, the slim chances of trying even one of the marathon puzzles have become even slimmer.

No partial bonus this time?

There is no requirement that all cells need to be used for numberlink, and there are plenty of examples where all squares haven't been used, however I'd say it's pretty likely that all the cells will be used in the answer keys at least, given that oversight. If you read MellowMelon's primer, you can decide for yourself whether this extra information will be of any practical use. :)

The "marathon puzzles" are big enough to sensibly fill an A4 page, without being too small. Motris is right in assuming they are big, but not THAT big.

rakesh_rai - 2010-10-06 9:25 AM
No partial bonus this time?

After discussing with Tom, this is what we decided.
Keeping in mind that WPC is only few weeks away where you *mostly* get 0 for a wrong answer, there is no partial bonus this time.
Also the bonus system is already fairly complex with the marathon puzzles.

Announcements

1. For HEYAWAKE in main section -
The answer key will be different that what it is specified in the IB

New Answer key: Enter the number of shaded cells in the 3th row, followed by the number of shaded cells in the 3rd column.

For the example the answer is 0,2

2. For HEYAWAKE in marathon section
The answer key is same as what it was mentioned in the IB. Enter the number of shaded cells in the marked rooms.

3. For Kakuro (both main and marathon section)
Instead of rows / columns, some sums will be marked. Players need to enter the digits for them.

Answer Key : Digits in marked horizontal sum 11, followed by digits in marked vertical Sum 24
For the example posted above : The answer is 5132, 798

The puzzle booklet will be uploaded around mid-night (IST).

For all puzzles where rows and columns are to be entered - they will be explicitly marked in the puzzle booklet by arrows.

The puzzles in the booklet will be sorted in ascending order of points.
P01 - Numberlink
P02 - Hashi
P03 - Sudoku
P04 - Surarumo
P05 - Akari
P06 - Masyu
P07 - Fillomino
P08 - Hitori
P09 - Slitherlink
P10 - Shikaku
P11 - Yajilin
P12 - Nurikabe
P13 - Kakuro
P14 - Yajilin
P15 - Heyawake
P16 - LITS
P17 - Nurikabe
P18 - Slitherlink

Password protected pdfs uploaded.
Note that the marathon puzzles are in a separate pdf.
~~Both the pds share the same password (which obviously will be displayed after you start the test)~~

Password for marathon pdf is different than main puzzle pdf. Both passwords will be displayed after you start the test

edited by debmohanty at 2010-10-09 6:20 PM

At this point, I'd just like to thank all the help and support I got from Deb and testers - absolutely top stuff guys and this wouldn't have happened without you!

"Nikoli Selection" has started. All the best to everyone.

We would like to apologize for mistakes in some of the puzzles.
1) The LITS image in the pdf is incorrect. We have uploaded an updated pdf. So all participants who are yet to participate please download the updated version.
2) The Nurikabe 10X10 puzzle is incorrect.
3) The Numberlinks puzzle has multiple solutions.
4) The Heyawake marathon puzzle is incorrect.

Extremely sorry for participants have already taken the test. I am sure you must have had a great time solving the rest of the puzzles. Hope it will serve as great practice for the WPC.

Password for marathon pdf is different than main puzzle pdf. Both passwords will be displayed after you start the test

Meanwhile we have also double checked all the other puzzles.
So all participants can proceed confidently with the puzzles without having to worry about inaccuracy or non uniqueness.

amitsowani - 2010-10-09 3:24 PM

1) The LITS image in the pdf is incorrect. We have uploaded an updated pdf. So all participants who are yet to participate please download the updated version.
2) The Nurikabe 10X10 puzzle is incorrect.
3) The Numberlinks puzzle has multiple solutions.

I am yet to take the test. It seems the updated pdf will have correct grid for LITS. As regard Nurikabe and Numberlinks - how are the points going to be awarded for these puzzles?

Frankly, I am a bit disappointed by the mistakes, as I wasted some time trying to fix the nurikabe and the LITS is a lot of points, but then again it's not like I was going to win anything anyway. I'll just solve the corrected versions and when I see my low score I'll have an excuse :P Still, I hope the people responsible take something out of this and be more careful next time :)

I haven't even started the marathon puzzles. Judging by Tom's post yesterday, I'm in for a treat :)

StGeorge - 2010-10-09 4:07 PM

Frankly, I am a bit disappointed by the mistakes, as I wasted some time trying to fix the nurikabe and the LITS is a lot of points, but then again it's not like I was going to win anything anyway. I'll just solve the corrected versions and when I see my low score I'll have an excuse :P Still, I hope the people responsible take something out of this and be more careful next time :)

We understand yours frustration about spending time on those two puzzles.
After the announcement, we hope that players who are yet to play will enjoy remaining puzzles.

I will take the blame here for this disaster - just not good enough I'm afraid.

We are currently discussing what to do. I have proposed the following:

-the nurikabe and numberlink are broken beyond repair and ought to be removed from the test (bringing the total score for the first section down to 920). Participants who have already finished the test should be compensated for the wasted time.

-the LITS is fixable. What will happen here is either the same as for the numberlink and the nurikabe - or else a new PB will be uploaded, and all earlier participants will be awarded the full points.

Once again, my sincerest apologies

I opened the first file but I have trouble with opening the marathon file. I downloaded it again but it does not accept the password (which was said to be common for both files). Is there something that I am missing?

yureklis - 2010-10-09 5:30 PM

I opened the first file but I have trouble with opening the marathon file. I downloaded it again but it does not accept the password (which was said to be common for both files). Is there something that I am missing?

Sent you password for marathon. check your forum inbox

Both the files have 2 different passwords now. Both passwords are displayed in the submission page after you start the test.

Reposting to make sure that everyone has read this post:

1) The LITS image in the pdf is incorrect. We have uploaded an updated pdf. So all participants who are yet to participate please download the updated version.
2) The Nurikabe 10X10 puzzle is incorrect.
3) The Numberlinks puzzle has multiple solutions.
4) The Heyawake marathon puzzle is incorrect.

Password for marathon pdf is different than main puzzle pdf. Both passwords will be displayed after you start the test

A good set of puzzle, i like it! I have done only a stupid error in hashi'answer key; i have entered the number of all double bridges.
Good luck to everyone!

I had the bad luck to solve the wrong PDF.

This is what I found:
#1 Numberlink - multiple solutions
When I realized it, I just found a solution that is using all cells and got points
#5 Akari - 4 solutions
For luck, all solutions have the same answer, so no problems with it
#12 Nurikabe - wrong image
I spent a lot of time on it. After time limit I solved the bigger Nurikabe for about 1/3 of the time I spent on this.
Actually, it's very easily fixable: just change '4' to '3' at R5C10
#16 LITS
I also spent some time until found it's wrong (one small line, but a big difference)

For anyone wondering what the big heyawake should have looked like:

Puzzle: http://www.warwick.ac.uk/~marear/36x20_heyawake.png
(and solution: http://www.warwick.ac.uk/~marear/36x20_heyawake_solution.png)

Please accept this as something of an apology :)

Deyan - 2010-10-09 11:15 PM

I had the bad luck to solve the wrong PDF.
#5 Akari - 4 solutions
For luck, all solutions have the same answer, so no problems with it

Sorry again about the problems.
#5 Akari has one solution. Please check your email.

debmohanty - 2010-10-09 9:06 PM

Deyan - 2010-10-09 11:15 PM

I had the bad luck to solve the wrong PDF.
#5 Akari - 4 solutions
For luck, all solutions have the same answer, so no problems with it

Sorry again about the problems.
#5 Akari has one solution. Please check your email.

Oops

You are right. I should change my notation for this puzzle.

The heyawake marathon was wrong? I didn't notice. It did take me quite a while to solve it - about 75 minutes - but I didn't see any mistakes. I'm sure I can easily be missing something and the correct version that Tom posted looks quite a bit different. Can someone tell me what the mistake is? Or is it that the one in the booklet is still a valid heyawake, just not the one that was intended? That would be a weird happenstance :)

I didn't notice either

- until it was too late.

There was a thing quite early on in the solve where you have a choice between either entirely surrounding an empty square with shaded squares, or else leaving 3 rooms empty in a row. The latter option was apparently quite subtle as I must have passed over it at least four or five times. Either that, or I'm an idiot.

The new version is basically a fiddle to change as little of the solving experience (after wrongly assuming the 3 empty rooms in a row) as possible - I'd estimate about 80% of the puzzle solves the same.

Edited by detuned 2010-10-10 5:39 AM

I obviously had the benefit of the "improved" test, but that won't keep me from my typical counting error (on the highest possible valued puzzle to boot). Got through all the solvable puzzles though. I think the marathon Kakuro was guilty of being too cute (not a good thing in a competition), but otherwise a lot of very fun puzzles to solve. Thanks for the puzzles Tom.

Edited by motris 2010-10-10 10:25 AM

Yeah, I found the spot and fixed it up with the new image, it should be ok now :)

By the way, the masyu marathon was pretty fun, I had a couple of warm, fuzzy "Oooh" moments solving it :P

I made it too although my PC froze as soon as I copy/pasted the pw. Had to reset and reboot and lost 5-6 minutes. Therefore I guess this time motris will beat me

Nice set of puzzles, although I did not always find a straight relationship between the points awarded and the difficulty level. Thanks Tom, better luck for the future

stefano
ps: how do I rate the puzzles?

Edited by forcolin 2010-10-10 2:55 PM

Nice set of puzzles. Made one error while submitting the answer to lost 100 points. Do take care while submitting your answers.

forcolin - 2010-10-10 2:54 PM
ps: how do I rate the puzzles?

In the submission page, below each puzzle name there are 10 dots.
The left-most dot is for 1-star and the right-most dot is for 10-stars. You can move your mouse over the dot to see.

amitsowani - 2010-10-09 6:03 PM

Reposting to make sure that everyone has read this post:

1) The LITS image in the pdf is incorrect. We have uploaded an updated pdf. So all participants who are yet to participate please download the updated version.
2) The Nurikabe 10X10 puzzle is incorrect.
3) The Numberlinks puzzle has multiple solutions.
4) The Heyawake marathon puzzle is incorrect.

Password for marathon pdf is different than main puzzle pdf. Both passwords will be displayed after you start the test

So for the Numberlink puzzle it means that any correct solution will be accepted and points will be awarded?
Or is that puzzle out of the competition like the incorrect ones?

Since you uploaded a new test booklet with a corrected LITS, are you going to somehow adjust the scores of those who completed the test before the new PDF was uploaded?

If you start the competition now, should you just skip the broken puzzles or are there still points available for these anyway?

We will consider points only for the updated puzzle booklet.
Points will be adjusted for all participants who participated in the test before the updated booklet was made available.

Results are published -
http://logicmastersindia.com/M201010P1/score.asp

We've followed a simple method
Nurikabe = 0 points for all
NumberLinks = 20 if player solved with old pdf and answer startsed with 1114, 0 if player solved with new pdf

This may not be the fairest way, but I guess there is no fair way to compute how much time a player spent on broken puzzle to compensate them for that.

We've disabled the ranks this time - you can sort by Points though.

Thank you everyone for participating.
And we (debmohanty, amitsowani, detuned) apologize again for the mistakes which could have been avoided.

There were 184 participants - 151 of whom got non-zero scores.

Here are some stats :
of countries - 35.
Top 3 (Based on #of non-zero entries)
Ind - 21
Japan - 18
USA - 16

Beginning of last week there were many new users registering from Japan that at one point I was thinking there will be more participants than Japan than India.
But Japan has highest Avg Score "754", and it won't be difficult to imagine how famous Nikoli is there.

Please provide feedback about the puzzles.
If anyone needs hints / steps to solve any puzzles, please don't hesitate to post here.

From the score page, it looks LITS is the least solved puzzle (okay, after the new pdf is uploaded)
No prizes for guessing the most solved puzzle - yes it is Sudoku!
P18 - Slitherlink was most incorrectly entered puzzle.

Hi Organizers,

first if all hats off for preparing such a wonderful puzzle set.

I have one doubt regaring the MASYU, It also has a multiple answers.

please tell me how can post it, so that you can correct me if i am wrong.

awaiting for the next test.

3 Cheers,
Keshav

@Keshav : I assume you are talking about P06 Masyu, because that is marked as 0 for you. We are absolutely certain that the P06 Masyu is correct and has only one solution.
You can upload your other solution (in image format) in this forum.

Hi,

I am extremely sorry, misunderstud the rule, i just read it should take 90 degree turn in Black circle and should not turn in white circle.

Thanks a lot for your reply.

Best Regards,
Keshav

debmohanty - 2010-10-08 9:01 AM

Announcements

1. For HEYAWAKE in main section -
The answer key will be different that what it is specified in the IB

New Answer key: Enter the number of shaded cells in the 3th row, followed by the number of shaded cells in the 3rd column.

For the example the answer is 0,2

[...]

This post sort of tripped me up. Apparently, it was not the 3rd row and column but the ones specified in the PB. I guess I must have misunderstood, I actually had the correct answer until I noticed the huge red announcement in the sidebar. :D Oh well.

I've never solved Nikoli puzzles, and keenly realized the importance of experience.
Especially, Akari and Heyawake (which I couldn't solve within the time-limit) were thought to be tough for non-Nikolist.

Anyway, Thank you for the nice puzzles!
Yuhei Kusui