Yin Yang U-Bahn [Secret Satan #1]
(Published on 3. January 2025, 13:50 by Christounet)
This is the first part of the gift I made for Piatato for the Secret Satan event. This puzzle was made as a warm-up for a larger puzzle I will publish in the coming days. I am of course publishing this with the permission and encouragement of my victim ! Enjoy :)
The puzzle :
Play on Penpa (answer check with green lines for the U-Bahn).
Rules :
Yin Yang : shade some cells such that all shaded cells are orthogonally connected, all unshaded cells are orthogonally connected, and no 2x2 area is fully shaded or fully unshaded.
U-Bahn : Draw a totally connected loop network through the centers of some cells, which may branch or turn, but may not have any dead ends.
Interaction : For each row/column, the clues outside the grid are given only for the shaded or unshaded cells, and it is up to the solver to determine to which they apply. A clue indicates how many times the corresponding line shape (i.e. a cross, branch, straight line, or turn) appears in the corresponding row or column, irrespective of the line shape's rotation.
The red P is a strictly positive digit. Note : besides being a strictly positive digit, that P has no other function in the puzzle. I just used it to create the access code to the main puzzle in my gift, and kept it for the solution code of this one.
Example puzzle:
Play on Penpa (answer check with green lines for the U-Bahn).
Note : the corner pencil marks are not needed for the solve or answer check. They are a way of notating that I use while solving this kind of puzzle, and it is useful here to keep track of the sums.
Solution code: Number of empty cells in each row, from top to bottom, followed by the result of this calculation : 6*P*number of times the U-Bahn network crosses between shaded and unshaded cells. (In the example, it crosses 14 times)
Comments
on 11. January 2025, 21:07 by Agent
Great puzzle, a nice introduction to the satanic follow-up!
on 6. January 2025, 20:55 by MaizeGator
This puzzle exemplifies Christounet's signature setting style, in which he displays exacting control over when ambiguities are resolved. An excellent mix of yin-yang and u-bahn logic, where knowing the secrets of each genre is important. I am sufficiently terrified for part 2!
on 6. January 2025, 19:51 by Christounet
Solution code description
on 4. January 2025, 15:28 by Christounet
Fixed example puzzle
on 4. January 2025, 04:36 by RJBlarmo
Lots of cool interactions in this warm-up, looking forward to the next one!
on 3. January 2025, 23:34 by ONeill
Cool puzzle, I’m sure the larger one will be very satanic!
on 3. January 2025, 20:47 by Mark Sweep
Very interesting! Looking forward to the main puzzle :)
on 3. January 2025, 18:53 by Fisherman
Do you mean Secret Santa?
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No. I do mean Satan. It's another event held on CTC discord, where people exchange rather harder, more evil puzzles. This warm up is not too evil though.
on 3. January 2025, 15:24 by goodcity
I wasn't fully familiar with the U-Bahn before this puzzle, but I loved the interaction between the two rulesets. Every deduction was challenging but rewarding!
Loved it !
on 3. January 2025, 13:58 by Piatato
This warm-up puzzle is already a great puzzle that gave me a good challenge and a huge amount of fun! The ruleset makes for fun interactions, and also a lot of uncertainty that makes the solve engaging throughout! Thanks a lot again!
