New sudoku variant: Earthquake
(Published on 14. March 2021, 05:58 by grkles)
Earthquake 0: Tremor
Normal sudoku rules apply. Treat digits in the grid as buildings of that height. After an earthquake, every building in the grid of height 5 or more has fallen down. Each of those buildings fell in one of the four cardinal directions, extending in a straight line a distance equal to its height, beginning in a cell orthogonally adjacent to its original cell. (It starts next to its original cell, leaving 0 stories behind.)
At least one story of each fallen building fell outside the grid, and the numbers outside the grid indicate how many total stories fell out in that direction from that row or column. Multiple buildings may contribute to each total, and a blank outside the grid is equivalent to a 0.
Cells in the grid that were hit by a fallen building were completely destroyed. The given digits are the only buildings still standing after the earthquake. Can you rebuild the city and return each building to its original height?
Play online at f-puzzles or penpa. When solving on f-puzzles, I recommend highlighting buildings to indicate the direction they fell, and highlighting destroyed cells as well. When solving on penpa, you can use arrows to indicate the falling direction (the Shape -> Arrow -> Arrow Tips tool works particularly well for this).
I've also created a solution guide google doc; this intro puzzle is easily solvable without it, but the guide demonstrates in detail the kinds of logical deductions required to solve an Earthquake Sudoku.
Seismology
Normal sudoku rules apply. Treat digits in the grid as buildings of that height. After an earthquake, every building in the grid of height 6 or more has fallen down. Each of those buildings fell in one of the four cardinal directions, extending in a straight line a distance equal to its height, beginning in a cell orthogonally adjacent to its original cell. (It starts next to its original cell, leaving 0 stories behind.)
At least one story of each fallen building fell outside the grid, and the numbers outside the grid indicate how many total stories fell out in that direction from that row or column. Multiple buildings may contribute to each total, and a blank outside the grid is equivalent to a 0.
Cells in the grid that were hit by a fallen building were completely destroyed. The given digits are the only buildings still standing after the earthquake. Can you rebuild the city and return each building to its original height?
Play online at f-puzzles or penpa. When solving on f-puzzles, I recommend highlighting buildings to indicate the direction they fell, and highlighting destroyed cells as well. When solving on penpa, you can use arrows to indicate the falling direction (the Shape -> Arrow -> Arrow Tips tool works particularly well for this).
I've also created a solution guide google doc, if you get stuck or want to compare your solve path with mine.
Solution code: Column 8 of Seismology, then row 4 of Tremor.
Comments
on 4. March 2023, 01:56 by Playmaker6174
I expected that this would take me a long while to digest the idea and yeah I was totally right, still the solve path from the main one was surprisingly smooth and there were couple of funny moments in the later half too x)
on 20. November 2021, 23:01 by Vebby
Really cool and clever variant! Thanks grkles! :)
on 27. September 2021, 15:24 by Piatato
Superb construction! After understanding the ruleset, the puzzle in itself isn't too confusing, although I did manage to break it a couple of times due to a characteristic lack of diligence. I had great fun solving it anyway!
on 19. March 2021, 01:25 by grkles
Updating the image html to look nicer (thanks, glum_hippo!)
on 15. March 2021, 07:54 by PrimeWeasel
@cdwg2000
I didn't spot the inconsistent 3, I think it was PixelPlucker. grkles is in a different time zone, so he was asleep, and I thought it best to do some responding for him. He responded later with the edited comments.
on 14. March 2021, 13:58 by cdwg2000
@PrimeWeasel
Thanks.
on 14. March 2021, 13:26 by cdwg2000
@PrimeWeasel
I have carefully checked many times. In the rules I understand, all the conditions are met. I don't know what went wrong. I posted my answer. If you are convenient to check it for me, thank you!
~ Hi cdwg2000, thanks so much for the solve! I've checked over your solution and in Seismology, you have two 3s in column 4. All your falling buildings are placed correctly, though!
on 14. March 2021, 12:56 by henrypijames
"Not falling at the same time" doesn't work, as one would destroy the other, as specified by the rules. (Unless we assume a world where time is not one-dimensional, which would be even weirder than selective dark matter.)
on 14. March 2021, 12:21 by PrimeWeasel
@cdwg2000 that's not the solution code I had, it's close though. Have you made sure all digits lower than 6 that are not given are destroyed?
on 14. March 2021, 12:18 by PrimeWeasel
I see what you mean Henry. Best viewed as them not falling at the same time I guess. I've made 4 or 5 earthquakes like this and have gotten used to the concept and never thought much about the visual problems that occur
on 14. March 2021, 12:09 by henrypijames
So if you have a 8 and a 9 next to each other, and they fall in each other's direction, they would just do through each other as if they were made of dark matter? But at the same time they interact with lower buildings (as in destroy them) so not so dark-matterly after all. That's most certainly not intuitive and needs to be make clear explicitly in the rules.
on 14. March 2021, 11:06 by PrimeWeasel
Hi Henry, they all fall, there is no order, and they do not influence each other.
If you take the 14 for example next to row 4. That could mean (e.g) a 9 in colum 9 which would contribute to 9 stories falling outside the grid. You will need 5 more, which could come from a 6 in column 8 (1 stories falls in the grid), or a 7 in column 7 (2 stories fall in the grid), or an 8 in column 6. They do not hit each other, they just contribute to the amount of stories outside the grid.
on 14. March 2021, 10:23 by henrypijames
I think this ruleset really needs a detailed example outlining the process and various corner cases of the earthquake.
It's particularly unclear in which order the tall buildings fall. If building A falls into building B, does A fall first and destroy B, which then couldn't fall itself, or does B fall first so they both fall? What criteria(s) decides the order of fall? What if A falls into B, B onto C, C onto D and D onto A again - is such a circle allowed?
~ Hi Henry! Sorry for the confusion. The intention is that the order in which the buildings fall doesn't matter. Each cell in the grid is in one of three categories:
1. A building that fell.
2. A building that was too small to fall itself, but that was in the path of a falling building.
3. A building that was too small to fall itself, and wasn't in the path of any other falling building.
The order is then "whatever order is needed to achieve this configuration", which is functionally identical to having the falling buildings pass through each other without colliding, while destroying the buildings in their path that were too small to fall.
I agree this doesn't make physical sense (because the falling buildings selectively interact with their surroundings), but it definitely works for the purposes of solving the puzzle!
I hope this helps
on 14. March 2021, 08:38 by PixelPlucker
Hello there!
~ Hi! :D
on 14. March 2021, 08:37 by PrimeWeasel
Finally, grkles is here! Earthquakes are such fun. Try it y'all!
on 14. March 2021, 06:03 by grkles
Fixed the broken html tags for links to solution guides.
