June 19th, 2009

art of sudoku

Sacrebleu and the Friday Puzzle: Yajilin-Battleship

Yesterday someone pointed me to the French WPC Qualifier as additional practice. I took a quick peek and was pleasantly surprised to find that there were more Hashiwokakuro and Total Masyu on there in the list of puzzles. Then I looked at the puzzles and saw that my blog examples had been reused in entirety (without credit given) and authorship given in the solutions instead to Jean-Louis Legrand. He stole my mystery KenKen too. A little research suggests he has copied my styles before (he did a Mastermindoku in 2008) which is fine with me. Copying styles is gray area, and should give some credit to the originator, but I welcome any new puzzles in ideas I've shared here. Copying my exact puzzles is not! I'm seriously upset by it, disappointed in the French organizers as it compromises their championship to have 5 puzzles that were already out there in the public, and while I've sent email along the proper channels to get the details behind this matter (and will get the authorship issue fixed), I felt the need to vent my frustration here as well.

Anyway, for today's Friday puzzle, when everyone will want to be discussing the rules for Saturday's test soon, I thought I'd do a variation on two types that seem to be on the USPC every year in recent memory: Yajilin-Battleship.

In these two puzzles (the first very easy, the second less so), place the fleet of ships into the grid so that no ships touch, even diagonally (note this is different than the yajilin black square rule where diagonal touching is allowed), and so that each numbered arrow gives the number of ship segments in the indicated direction. The remaining empty white squares must form a single closed loop. Note: In the second puzzle two ships and two seas are given to you in the grid; the "seas" are necessarily in the loop.

art of sudoku

USPC Preview - Instruction Impressions

So, I'll just "live blog" my thoughts as I read through the instructions for the first time. With the usual password fun9ss appearing even for the instructions, I expect another great password on the lines of the key lime pie one for tomorrow's test.

1. 23 puzzles (last year 20), total of 400 points (last year 365). I've never been over 400 so this will be the year to get to there with my highest score to date. The addition of low-valued puzzles seems to account for the change. The old standard of adding bonus points to puzzles to encourage their solution seems to have really fallen out of favor.

2. The Nikoli addition does mean nikoli versions of many of the common types (so US designer versions of "variations" on those, since Nikoli prefers the pure form of their puzzles with as few instructions as possible). So, Sudoku, Corral, Masyu, and somehow a 25-point Yajilin will all be on the test from our Japanese friends.

3. I am much less excited, as any reader of this blog knows, by having an "official" Calcudoku (#3). The "non-associativity of subtraction/division" rules are in play so, yeah, don't get confused by my missing operation puzzles where I recognized non-commutativity is the actual problem and this two-cell constraint is silly.

4. No word search (my favorite type is gone!) but several word fill-ins including the now ever popular Magic R version of a word fill-in that's been on Turkish and German tests too (although with no touching constraint and a single diagonal direction allowed as well).

5. A counting "puzzle" (screams NO!!!!!!!!). The author doesn't even want to be known - for shame! Until a name is given, I'm assuming Baxter.

6. A Craig Kasper puzzle that involves diagonal information, like his past Atomic Fusion that "spoiled" my 2006 (screams DI-AGONY!!!!!!). His other contributions (word fill-ins/criss-crosses) should be fine.

7. The Friedman puzzles seem approachable (I say this at my own risk of foot in mouth disease). Coordinate pairs looks like dot triangles but only has line segments so I bet I can do it. C Notes is exactly like the 100 puzzles that have occured on WPC Bulgaria and Belarus. The 2-3 Maze is probably the unknown variable, but I deal rather well with logic mazes.

8. Eminent D'OHmain looks like fun (and it looks like Adam, if I didn't already know authorship, enjoys capitalizing parts of his puzzles titles given last year's SuDON'Tku and this year's SuDUOku). SuDUOku seems another tough twist on last year's version. I have a lot of surplus/deficit sudoku experience from working with Wei-Hwa on these kinds of puzzles, so I think I'll do alright. I won't advise how to solve this puzzle yet though until I make one as I know last year I threw people off with SuDON'Tku.

9. Triangular Skyscrapers amazingly uses a tiling constraint I put into my "Mosaic Sudoku" in the upcoming Sudoku Masterpieces where each triangle orientation has only one of a digit. I also put in two colors with a labeled set of pieces so you'd know which ones of a particular triangle shape may be a particular digit but I doubt that additional use of color will go on here. Since I got that to my publisher before Aziz's puzzle here and since he would have no way of seeing my puzzles, I think we tie for the concept of a triangulated square grid that works this way. The Four Square variation looks like fun too (although here is The Typo(TM) in the instructions, as Skyscrapers is #8, not #11, since I definitely remember what #11 is). While I realize the dark squares indicate the turning snake, did anyone else initially wonder if primes would be important for this snake before reading the instructions?

10. Tuller follows up his fabulous Sheep in Fences last year with the addition of wolves (next year, obviously wolves dressed as false sheep!). Now the inside/outside shading rules of slitherlink that tend to be underused will be very important. His inside-outside corral will also be a good challenge, and I really look forward to it.

So, overall strategy/goal is still obviously to finish the test, but I'll be banking the big pointers early. Last year I did Spot The Differences back to the front and then did the hardest puzzles going forward. I imagine the same here. I'm sure I'll skip over the -5 pointer #11 until the end. Best of luck to everyone.