Nikoli Hurdles 2: Last stretch

nh2offbannerOnly 5 days to go!
I have sent replies to all entries that I’ve received thus far. If you believe you have submitted but have not yet receive an e-mail from me, please resend your entry.
rcroyYou may have noticed the label: “Reader’s Choice” in Masyu and Slitherlink. Reader’s Choice provides an opportunity to make sure your favourite puzzle appear in the next set of hurdles. Below are five number-filling puzzle types.
Which puzzles would you like to see in Nikoli Hurdles 3?
I’ll collect your votes and announce the tally later on. You can choose up to 3 types.

Check back in a few days for the announcing of Nikoli Hurdles 2 results!

Half way to go

 

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We are approaching half way into Nikoli Hurdles 2. All entries that were sent in have been replied to.
I usually take up to 3 days to send a reply, so if you have submitted an entry and not yet receive a confirmation e-mail – please resend your entry.
Also, make sure to spell your e-mail address correctly, otherwise my reply might not reach you.
Thank you all for the entries that are coming in, I enjoy keeping a tally of your records.

If you have any worries, feel free to send me an e-mail about it.
Happy puzzling!

Runners, welcome!

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Welcome to another set of Nikoli Hurdles!
For the next 29 days, a track of 8 Nikoli puzzles will be opened for you to solve. Starting at Puzzle 1, the solution will be used to open Puzzle 2. The answer to Puzzle 2 will open Puzzle 3 and so on.

The different puzzle types will require different answer key extractions so pay attention to those. An entry form will be at the finish line for those who complete the entire track. More details can be found at the About page on the menu above.
Don’t forget to use capital letters, when required.

I will always be available to answer questions, so you can drop those in the comments or email me at roygbivpuzzles (at) gmail (dot) com. A prize will go to one lucky winner after this event ends.

ETA (27/9/14): 8 hours into the contest, early runners had sent me problems about some of the puzzles.
Puzzle 2 had a little tweak in one of its clues, I’m surprised people could still proceed. The last Puzzle 8 had one slight drawing error. Both puzzles have been fixed. Puzzle 7 was questioned as well, but upon reinspection, it is not broken and has a unique solution.
The finish line had the wrong password for about 8 hours, but it is now fixed. I apologize for all these mistakes.

Puzzles on Patreon

Ever since Grandmaster Puzzles offered opportunities to buy rewards on Patreon, we see more puzzle providers following the trend. Currently Grandmaster Puzzles enjoy a little over $500 a month of support from its audience. Considering that the patrons get a very good quality puzzle almost daily, a few dollars seem like a bargain. GMlogo

As a patron myself, I do enjoy the weekly puzzle PDFs sent promptly to my inbox before they are released the next week on GMP. You can also get access to solutions, walkthroughs, monthly large puzzles and even puzzle-packed PDF booklets. I can tell a lot of work has been put to maintain the standards at GMP so if you’re not already a patron, I highly recommend this innovative source.

In shocking contrast to Grandmaster Puzzles, Logic Masters India (LMI) has 9 patrons. Nine??
LMI has been like a home to me for the last 4 years and has over 6000 registered users with hundreds of active solvers logging in every month.

LMINewLogoLMI offer cute puzzle packs containing puzzle types from the latest online tests. The incentives on their Patreon page may not be as attractive as the offerings from GMP, but LMI has done such a hugely demanding job running regular online tests and constantly improving their web formats that active users on LMI should reconsider becoming a patron.

Most recently, the folks behind Akil Oyunlari launched Meraklisina Akil Oyunlari. I was late to discover the magazine when I first contributed to issue 76. 4 issues later, Akil Oyunlari underwent a drastic format change and all of sudden it became a children’s magazine. Growing up solving kids’ puzzle magazines, I realize how important these magazines play a role in attracting a child to still be a puzzler when he/she grows up.

Logo2Nonetheless I had to order a few back issues to satisfy my puzzle craving as ones in recent format are evidently not aimed at experienced readers. But now it is back, a 10-a-year online PDF puzzle magazine with logic puzzles for expert-level solvers. If anyone knows of any magazine containing just logic puzzles, do let me know. So far I know of Akil Oyunlari, Breinbrekers (which I saw the Dutch team solve at last year’s WPC – is there a way to buy this without going to Holland?) and a few titles by Gareth Moore at Puzzle Xtra.

Show your support and keep the puzzling world spinning.

In SOTR news…

previewnh2Nikoli Hurdles 2 is on its last corner of editing and I will post details about this event soon. Grab some Nikoli books and start warming up!

Light Read #3 – Let me flip that

So I was staring at the 2nd Pentopia of the WPC 2013 practise test written by Ko Okamoto thinking how I ended up with multiple solutions. I reread the rules at least four times and came up empty. How odd, I thought, since I have solved a few Pentopias before. I looked at the first Pentopia of the set, which was straightforward, and found nothing wrong.

Hmmmm…

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Pentopia by Ko Okamoto (Oct 2013)

A fifth look at the rules saw me emphasizing the last sentence: pentominoes may be rotated but NOT reflected. There we go. The puzzle solved itself.

There’s nothing upsetting about forbidding reflection, but it leaves an empty room for a flexibility-loving nut like me. When I construct puzzles using polyminoes I have Blokus pieces handy to quickly prove uniqueness. Blokus players will no doubt have the habit of twisting and reflecting polyminoes in their heads to optimize those nasty land-grabbing moves.

Any other puzzlers out there who plays Blokus?

Any other puzzlers out there who plays Blokus?

Which leads me to my point: why disallow reflection of pentominoes in puzzles?
Reflection affects 2 tetrominoes, namely the L (or J) and S (or Z), and thankfully most tetromino puzzles forgive reflection. Imagine a LITS where S and Z are two different pieces; there goes a boatload of beautiful deductions.

However when we’re dealing with pentominoes, 7 of 12 pieces form a “different” shape when they are flipped over. This reduces the number of possible orientations rather significantly. Puzzles with this rule will be easier since there will be less possible positions. Not only for solvers, but this also cut authors some slack when constructing the said puzzle.

Have I been solving pentopias all these years without ever knowing is rule?
A quick check at Puzzle Para Site, since one would associate Pentopias with Bram De Laat, revealed that reflections are in fact allowed.
Good.

Maybe there are certain puzzle types where not allowing reflection is better. But for now, I’ll have my seven extra orientations, thanks.

Solutions to July Giants – Part 2/2

The menu is taken down, the puzzles are available in PDF attached in the previous post.
Picking up from the last post after the giant Masyu:

Snake Pit
Following such a complex Mastermind Tapa was a tall order. The giant Masyu was met with so much criticism that I had to rethink what I should post for the upcoming Medusa. Most were quick to point out that the giant puzzle was too simple and a lot less exciting that the Tapa they solved a few days earlier.

Originally planned for Medusa was a giant word search. However after receiving mails about how dull the Masyu was, one had to be arrogantly audacious to post a simple word search. I returned to the drawing board and whipped up Medusa’s Snake Pit. It took exactly 60 minutes to draft the whole puzzle.

I looked at the Snake Variation Contest authored by Serkan Yurekli to see which types were suitable in a giant grid. Snake puzzles usually involve clues outside the grid so my choices were rather limited. Masyu Snake was a no-go since Argus was already on the list of giants. I settled on the 5 variants and the puzzle was born.

medusaansMy intended break-in was in the left-hand portion of the Schlange. I wanted solvers to start off linking BB and JE to get their first toehold of the puzzle. The puzzle gods (Medusa?) didn’t agree with me and the obvious “3” of Slitherlink Snake at the bottom left hand corner was definitely a buzzkill. When I was test-solving the puzzle, almost none of my planned deductions were required at all. I imagine this happen all too often in giant puzzles. Life goes on.

I feared it might be too easy because of the heavily-constrained nature of Snake puzzles. So it was a relief to still see so many compliments. Antonis Lalatsas observed that this very quickly degenerated into a length constrained Arukone. Which is good because I like Arukone but suck at Snake puzzles.

Similarly Stefan Tomlins noted: It’s very clear there’s only one answer once you’ve got it (except for the remaining sliver of paranoia).

However the medal of courage has to go to Prasanna Seshadri who created extra work for himself: I solved on paint, and its a bit messy now.

Yuhei Kusui disagrees since: This is the most beautiful Medusa I have ever seen.


Fillomino Match-Ups
The final puzzle was Cerberus. The monster concept came before the puzzle so I thought about something with 3 heads. Maybe three overlapping Fillominos?
I had a brief look at the two Fillomino Fillia tests and scouted the 3 variants that were used. The idea of having a matchmaker-type of puzzle quickly worked itself out. No Rectangles was the first to be constructed and due to its nature, 1-cell and 2-cell regions were not allowed. I then realize how difficult it will be for the remaining puzzles. In order to mask early matching deductions, I was prohibited from using any 1 and 2 as clues in the other Fillominos!
Ouch. Otherwise, oh this puzzle has a 1 (or 2); therefore it cannot be the No Rectangles.

No-Rectangles Fillomino
fillo1ans
Depriving a Fillomino author from using 1 and 2 will make his life very difficult. I learnt this the hard way when Star Battle keeps getting broken. I ended up with that ugly clunk of 7s in the middle.

Star Battle Fillomino

fillo2ansAfter the 3 puzzles were made, I originally had in mind 3 more classics mixed in. Then after unsuccessfully attempting to write the first classic without the use of 1 and 2, I just gave up.

Odd Even Fillomino
fillo3ans
There were many different approaches to Cerberus.
Antonis Lalatsas shared his: I excluded grid 5 due to the interplay between clue 22 and the 563 triplet. This left only grid 6 respecting the Yin-Yangish border constraint of Odd-Even, which then solved quickly. Grid 2 was out next due to top 3 being forced straight and a single 2×2 remaining space for two stars on the top two rows. And that’s all I did logically.
The bottom right quarter of grid 1 looked woefully underconstrained unless I could force the middle 5s into different polyominos by bringing down the 4, and this quickly gave me a working Star Fillomino.

Emboldened, I randomly tried grid 3 as No Rectangles, working ccw from the 10 and failing in the three 3s to the left. I used the same failing logic to working effect this time on the remaining grid, which solved pleasantly.
Was there an obvious logical step (or three) I missed?

Short answer: to be honest I can’t remember. During test solving I remembered disproving all 3 fakes before solving each variants. I recalled solving all 6 grids under every rule to make sure they had one unique solution. Odd-Even was first if I remembered correctly and there was a toss-up between Star Battle and No-Rectangles. I didn’t check to see if a puzzle also work under another rule but apparently [Matej Uher]  found that grid 1 has multiple solution in no rectangular, so i try other possibility (star battle) :-/

Edison He mentioned I was stk (sic) for a while on the Star Fillomino. Was there any better way to get it besides assuming that the top right square is not filled by a star?

I agree that Star Battle was the hardest of the lot. I remembered the puzzle started from the bottom left and worked its way up. The last bit I recalled using guess-and-check to prove uniqueness so it was probably a similar method everyone used.

And lastly Ivan Koswara pointed out that people are used with Star Fillomino with two stars
Oops I forgot.

I finish this post with a funny comment from James McGowan who promptly finished all four giant puzzles.
With the body of the final monster at his feet, Jameus wiped the gore from his face and looked around. The sun shone through a gap in the clouds, somewhere a bird burst into song. Local villagers were weeping with joy, busty maidens swooned and flirted. “Now we feast!” he bellowed, and the crowd roared back its approval. It was a good day to be a puzzler…

I feel everyday’s a good day to be a puzzler.
With all the solutions posted, July Giants has now come to a close. My next event is in the works and originally planned for October. However, I have a hunch that it might be held near the end of this month if things continue to go smoothly.
Thanks for dropping by.
See you next time!

Solutions to July Giants – Part 1/2

PDF booklet of July Giants
Right here!

Tapa Mastermind
I was solving Akil Oyunlari issue 72 and a few pages from that issue were devoted to puzzles from the first Tapa Variations Contest. One of them was Mastermind Tapa which used 4 small classic Tapas. I didn’t finish the puzzle, but it was enough to get me thinking about the idea of this Hydra puzzle.

Hydra had 9 heads so I quickly settled on having 9 puzzles. I quickly decided that the centre would be the last puzzle to be solved and it should be a classic Tapa. I had 8 choices to make regarding the surrounding Tapas so I referred to the Tapa Variants list that Serkan compiled a year ago.

I jotted down a few appropriate variants and started from there. A big puzzle like this one would inevitably have several starting points but my original path started at Compass Tapa and Alternative Tapa. I’m sure everyone else’s experiences will vary.

hydraans

Personally this was my favourite puzzle as I thought all the grids worked out really well. I hoped Hydra wasn’t a walk-over and Thomas Powell concurs: I’m very slow at Tapa. That was 90 mins for me.

Masyu
This was the first giant Masyu I’ve made. I consulted some examples of giant puzzles to see what sizes were optimal. Most were 20×36 so I just went with that. I didn’t have any ruler on me so I dot the corners in my grid book and splashed in a few circles.

I tried to include as many patterns as I can; there’s a flower on the top left, next to it is a question mark, a wave of circles in the middle, a spiral, four random plus signs and an X down at the bottom right. When everything on paper was done, it was straight to the computer to draw up the grid. I entered the 20×36 dimension, started plugging in circles and… hold on. Why is there room left?

I looked down at my notebook and slapped my forehead. I left out 5 whole rows!

Well, I’m not going to dismantle the whole puzzle. You’ll just have to make do with a 20×31 Masyu instead.
argusmasyuansThe puzzle was represented by Argus Panoptes, a 100-eyed monster, so it was thematical to drop a trivia question about that. This was where my laziness to triple check came back to haunt me. The original question read, “In what part of your body is the choroid?”

I originally had conjunctiva or sclera in mind but there were too many/not enough space so I had to find a 7-letter part of the eye. And yes, the answer is EYE. The choroid is a thin layer between the retina and sclera. It turned out within one hour of posting, a few solvers pointed out extra letters in the string. Doh!

The puzzle was tweaked and the new question read, “In what part of your body is the optic disc?”

Introducing language into a logic puzzle will unsettle some solvers. I also learnt that the Russian translation of optic disc is…

Andrey Bogdanov: I didn’t know what “Optic Disc” is. The Russian name of the same item can be translated as “Blind spot” – nothing in common.

Edison He was one of few who enjoyed the puzzle and noticed…
Now, if only there had been 99 clues in the grid, so that we would have pierced each and every one of them exactly. But as it stands, we seem to have blinded a number of innocent bystanders.

 

July Giants Results – Part 4/4

It has been a fun July and I thank you all for participating. Honorary mentions go to; Andrey Bogdanov, Andrew Brecher, Jakub Hrazdira, Edison He, Ivan Koswara, Yuhei Kusui, Matt Lahut, Antonis Lalatsas, Ken Levine, James McGowan, Alex Pei, Willy Petrenko, John Reid, Prasanna Seshadri, Stefan Tomlins, Robert Vollmert and Nikola Zivanovic who correctly solved all 4 giants.

As for statistics that take in account earliest submissions; the early bird gold medal goes to Edison He (Hong Kong), silver to Ivan Koswara (Indonesia) and bronze to Ken Levine (USA). But the main winner, who will receive the Nikoli Puzzle the Giants 2014, will be determined by rock-paper-scissors. We have narrowed down the field to four potential winners and now it is time to announce the winner!

For the final time: rock…paper… scissors!
jgiantsfinalres
Congratulations to Jack Bross from USA!
He got defeated by Hydra early on but bounced back with 3 correct entries to the last 3 giants. He won the Cerberus tournament and ultimately the Champion’s Throne.

We now come to the end of another event. As usual, I will devote the next few posts looking back at the puzzles in greater detail. I plan to make a full PDF booklet of July Giants soon so I will keep the menu above until I complete that. Plans for the next event are well underway it is scheduled for October but things could change, updates will be made here.

A lot of my audience is in London for the WSC and WPC right now so safe travels everyone. Thanks for being with me throughout July and I look forward to seeing you next time.

July Giants Results – Part 3/4

We are about to find out the winner of Medusa. The final four were already introduced so without further ado… Rock paper scissors!
medusares2

Congratulations to Nikola Zivanovic from SerbiaHe will join the last battle for the throne later on.

Lastly, we had 28 solvers defeating Cerberus.
cerberes32
Four byes were awarded for the earliest submissions. There was a noticeable match-up between occupants of the throne; James and Yuhei, in the first round.
cerberr4You can also see a wild scuffle between Ivan and Prasanna in round two. And another tough battle for Ivan against Jack in the third round.

We have our last set of final four.
Andrey Bogdanov is the head of Russian puzzle club Diogen. When I first discovered logic puzzles, a few years before LMI existed; Diogen was one of few sites that were active at that time. It was a pleasure seeing his entry in my blog. Andrey’s opponent will be Jack Bross. Jack has been with SOTR since the early days of this blog and has continued his participation ever since. He has reached final four once, which was way back in Nikoli Hurdles (February 2013), where he was knocked out by the winner Prasanna.
The other side sees Giovanni Pagano, a fellow test solver when Ivan hosted Deception on LMI. July Giants is his first entry at SOTR and like me; he also actively solves word puzzles. Maybe I can lure him back with a word puzzle contest sometime later. Facing Giovanni is James McGowan who is looking to take a second spot in the finals. No introduction needed, he is probably solving some puzzles in a very competitive environment somewhere in London right now.

cerberresfinal

And… congratulations to Jack Bross from USA! 
He joins the three past winners to the Champion’s Throne. Which now looks like this:
ctprew

Exactly 24 hours from now the post revealing the winner will be posted. Sorry to keep you waiting this long, but processing and triple-checking the RPS hands took time. Worse, drawing each grid up took way longer than I anticipated. Nonetheless, I had fun. I hope you did too.

Don’t miss the final showdown tomorrow!

July Giants Results – Part 2/4

Continuing where we have left off.
Round 3 of Argus Panoptes, where 8 contenders remain:

argusres8Japan is a top 10 country that toggled the most visits at SOTR. Curiously, Yuhei Kusui is Japan’s first entry to any event I’ve ever hosted. The first seed will be up against Ken Levine, who you might recognize as “The Subro” where he solves puzzles at numerous blogs. In the other corner, Matej Uher, who once reached a crazy final in a RPS tournament earlier this year, will be facing Matt Lahut, a newcomer and July Giants is his first event.

Who will prevail? And the winner of Argus Panoptes is…

argusres4And the first-seed delivers! Yuhei Kusui from Japan occupies the second seat in the Champion’s Throne!

We now come to our third week to determine who will take the third spot. 27 people defeated Medusa so the bracket will award 5 byes to the earliest submissions.

medusares32There are two reasons why I use RPS as the method to determine the winner. Firstly, I enjoy the suspense while conducting them. Secondly, I just find “the winner from a random draw is so-and-so” such a plain way to end any contest. RPS not only introduces randomness but it also allows a little window of strategic play.

For example, in Argus Panoptes: James McGowan opted for PPSSSSSSSS and Matt Lahut reached the finals with PSSSSSSSSS. Coincidence?
Now in Medusa, 3 sneaky players adopted the same strategy.
Ken Levine: PPPPPPPPPP
Robert Vollmert: PPPPPPPPPP
Andrew Brecher: PPPPPPPPP
This explains why paper is so popular in my stats. Ben Wootten also did something similar: RRRRRRRRRR

Let’s see if this strategy works:
medusares4(Errata 14/8/14: Fixed incorrect symbols)
Nope! Ben got as far as the final 8 until he eventually had to face a paper. Matt Lahut, with a different set of hands, is once again in the final four! Could he take his revenge? He will be facing puzzle master Nikola Zivanovic. Nikola is one of SOTR’s top solvers who always came up short in these luck-based games. On the other side, Czech’s puzzle ace Jakub Hrazdira (known as “Gotroch” in the puzzle community) will take on Dylan Gibbs, who certainly exercised his beginner’s luck as Medusa was his first submission ever with SOTR.

Who will occupy the third seat in the Champion’s Throne?
To be continued