Puzzle 156: Killer Sudoku

Next weekend I’m running a pure Killer Sudoku contest at logic-masters.de. The idea was to give our Killer Sudoku experts a chance to shine. It’s 9 puzzles in 90 minutes from 6 authors, see the instruction booklet for further details. Thank you to Tom Collyer, Stefan Heine, DavidMcNeill, Eva Schuckert and Bernhard Seckinger for their contribution!

To get you in the mood, here’s one Killer Sudoku.

Rules Solve as a regular Sudoku. In addition, some cages are given. The cage clues indicate the sum of the digits within the cage. Digits can’t repeat within a cage.

Puzzle 155: Minesweeper-Tapa

Here’s another puzzle I made in preparation for the recent Logic Masters. It’s a Minesweeper Tapa, a type from the Tapa round on the contest.

In other news, results have now been posted: https://logic-masters.de/LM/2018_e_tabelle.php. (It seems linear time bonus really isn’t the right choice where players finish after a fraction of the round: On round 6 I took 3.5 minutes compared to the next player’s 5 minutes, for a factor 1.06 in points.)

Rules Solve as a regular Tapa, except the clues just specify the total number of shaded cells in the surrounding cells, as in Minesweeper.

Puzzle 154: The Largest Number

Posting from the evening after the 2018 German Logic Masters. It went decently well for me, with a third place after the main rounds which means I’m on the A-team again. My results on the two Rätselportal-rounds were bad as expected. On the other hand, finishing that fences sprint round first with quite a margin after 3:15 of 20:00 minutes was great. An unfortunate marking mistake in the final playoffs saw me lose a couple of minutes of time double-checking my correct solution. With no good way to fix this, I ended up fourth with the knowledge that first place was possible.

I made a couple of puzzles to prepare, two of which I’ve published on the Rätselportal already: A Japanese Sums/Masyu hybrid and a hand-constructed (with the help of a friend, thank you!) unclued 5×5 skyscraper blocks that I’m very happy with!

Some more I’ll post here. To start, here’s a The Largest Number. The type was introduced at the 2017 WPC in India. I don’t think I’ve seen one without given numbers before.

Rules Fill the grid with numbers such that each room contains the numbers from 1 to the size of the room. Equal numbers can not be next to each other horizontally or vertically. Circle the largest number in each room. Then also circled numbers can not be next to each other horizontally or vertically.

Puzzle 153: Friendly Sudoku

Here’s a new (?) Sudoku variant. Inspired by Sudoku N from the upcoming Sudoku Mahabharat. The 6×6 example there also solves uniquely by these rules.

Rules Solve as a regular Sudoku. Some pairs of numbers are friends. Dots mark all spots where two friends are next to each other.

Puzzle 152: Masyu No-Touch

Another one for the GP. This is a Masyu with the extra rule that unused cells can’t touch by edge.

Solve and check your solution here, or use PZV (but that doesn’t verify the no-touch rule).

Puzzle 151: Skyscraper-Nurikabe

We continue with the regular puzzle-a-month-on-the-first-of. Here’s a Skyscraper-Nurikabe, a practice puzzle for the upcoming Indian GP.

Rules Solve as a regular Nurikabe. Additionally, some skyscraper clues are given outside the grid. For these, consider the blocks of adjacent shaded cells within the corresponding row as skyscrapers with height equal to the number of cells in the block.

Or check the instruction booklet which includes an example.

You can solve online (of sorts) and check your code here.