Puzzle 69: Foxger’s Hybrid

Sashikabe example puzzle and solution

Sashikabe
Example puzzle and solution

Sashikabe Basically Sashigane and Nurikabe together. Shade some of the cells black so that the black cells form a Tapa wall (also known as a Nurikabe). The remaining white cells form several polyominoes each. Each polyomino must be of the shape of an L; formally, it is composed of an “elbow” of one square, with two “legs” of 1-cell width non-degenerate rectangles orthogonally adjacent to the elbow and are perpendicular to each other.

There are clues on the grid in form of arrows and circles; these squares must remain white. An arrow marks the end of some leg and shows the direction where the corresponding elbow is; for example, a left arrow means that a leg ends there and the elbow of that leg is located to the left of the square. A circle marks an elbow; a number inside a circle means that the polyomino containing that elbow has exactly that many squares.

Expected difficulty HardAnswerComment/E-mail if you want a solution to be published

Puzzle 69: Sashikabe

Puzzle 69: Foxger’s Hybrid
Sashikabe

Yay, a puzzle! It’s rated hard solely because it’s a rather unusual genre.

So… What’s with the title? This genre is invented by Grant Fikes aka glmathgrant, and is pretty obviously a hybrid. In addition, Grant’s online persona (Grant Badger Fox) is also a hybrid (fox and badger), so you can call “Foxger [is] Hybrid”, using “hybrid” as an adjective. So, yeah, lame title. I can’t think of a better one though.

Also, as you can see, I attempted a perfectly symmetrical clue arrangement. Turns out I need to use a single circle there (luckily still preserving symmetry of layout, but not the contents), but I’m quite happy with the result as the solution itself is satisfying.

Why do I construct this? A request by mathgrant, of course! He made a Sashikabe puzzle and challenged me to make one too, so here it is. Turns out constructing these is a pain. Perhaps because I put the condition of making the clues perfectly symmetric, but hey, I tend to like perfect layouts.

Anyway. TVC XIV and CTC 2013 on Logic Masters India are going on! If you like Tapa, you should give both a try. The latter needs a consistent online schedule if you want to score high, but if you’re not into competitive stuff, you can still solve them for fun. They are pretty amazing puzzles. On the other hand, the former is part of TVC 2013, a 4-part contest of Tapa variations that has run since 2010. So yeah, two big events are running now.

On a more personal note. I’m currently in KAIST, as you should have known if you read this blog regularly (the latest post about my experience in KAIST has been up for about 4 days now). My Orientation Week has just ended, and seems like it’s not too busy…yet. The first academic week will start next Monday, so let’s see whether I still have time to construct puzzles or not…

Well, that’s all for now. Stay tuned!

EDIT 27 September 2013: Grant Fikes got his Sashikabe puzzle published! I’ve testsolved it and it’s a very nice puzzle. Also, this is one part of my thanks to Grant due to a certain personal problem that I prefer not to be shared with general public, but basically Grant helped me with my problem. A lot of help. Next part will come later. :3

Deception Preview 8: Counting The Naturals

Domino Nurikabe Shade some cells black so the black cells form a tapa wall. No cell with a number may be shaded black. The black cells divide the white cells to several polyominoes (islands), all maximal (cannot be extended). Each island must have exactly one number that tells the size of the island. In addition, it must be possible to partition the black cells to dominoes. Such partition need not be unique, as long as there exists at lest one.

Answer key: Enter the lengths of the lines of black cells in the marked row/column. If the row/column has all/no black cells, enter 0.

Difficulty 3.5/10 • Target times 01:00 02:30 04:00 10:00
Solution Answer key (highlight →) 311,41PNG (not uploaded)ZIP of PDF (not uploaded)DOCX (not uploaded)

Deception Preview 8: Domino Nurikabe

Deception Preview 8: Counting The Naturals
Domino Nurikabe

Eighth preview puzzle. Try solving the puzzle with 18 changed to a question mark (indicating an unknown number). Otherwise, not much gimmick. Figuring out the top-right part is a little tricky though.

Special Puzzle 8: It’s Erased

Domino Nurikabe. Follow regular Nurikabe rules (color some cells black so black cells form a single polyomino and white cells form separate polyominoes (islands) so each island contains exactly one number which represents its size). In addition, the black cells must be able to be partitioned into non-overlapping dominoes. Question mark represents an unknown number.

Sky woke up. “Darn, I shouldn’t make puzzles that late. What, I think it was 1 AM or something when I fell asleep…”
He reviewed his puzzle, and noticed something was smudged. “Err, what’s the number in this cell supposed to be?”
“Hey Sky! Has the puzzle been made?” someone shouted from outside, shocking him.
“Oh ya right! Just a little fix!” Sky rushed to find the number in the erased cell, but he couldn’t get the actual number. Hesitantly, he erased the smudge, put a question mark in it, and gave it to his senior that leads The Daily Puzzle, otherwise known as Chaos at the Sky.
“Domino Nurikabe, with an unknown number. Seems legit. Let’s see,” and the boss, chaotic_iak, left. Sky returned to his home sadly.

Special Puzzle 8: It's Erased Domino Nurikabe

Special Puzzle 8: It’s Erased
Domino Nurikabe


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Puzzle 16: Domino Nurikabe

The actual Puzzle 16 that is not broken. Still Domino Nurikabe. This one is pretty hard IMO.

Follow regular Nurikabe rules. In addition, the stream can be partitioned into 1×2 dominoes.

Puzzle 16: Domino Nurikabe

My solution here is valid, but I’m not sure about whether there are multiple solutions or not because I used some large-scale logic (as in testing many choices while there is still a pretty large space left). Yay.