Roller Coaster Nurikabe
(Published on 24. February 2023, 19:32 by the_cogito)
Rules:
Place the digits 1-9 once each in every row and column.
Nurikabe:
- Every cell is either water or land. All water cells must be orthogonally connected, and no 2x2 area may be entirely water.
- Groups of orthogonally connected land cells form islands, which do not touch orthogonally, but may touch diagonally.
- Digits may not repeat on an island.
- Circled land cells indicate the size of their island.
- Circled water cells indicate the number of cells seen in cardinal directions from that cell, including itself. Land cells obstruct vision.
- An island may or may not contain any circled cells.
Roller Coaster:
- Draw a non-intersecting loop that travels orthogonally between the centers of some cells in the grid.
- Clues to the left of rows indicate the sum of digits on horizontal segments of the loop in that row, in the correct order.
- Clues above columns indicate the sum of digits on vertical segments of the loop in that column, in the correct order.
- A "?" may replace any value from 0-9, but no clue may have a leading zero.
- No straight segment of the loop may be entirely on water cells.
- Every island is visited by the loop exactly once.
Below is an example 6x6 puzzle demonstrating the ruleset in action:
And here are links for the example puzzle in case you want to try it yourself:
6x6 Penpa+
6x6 Sudokupad
And now for the main event:
Solve on Penpa+
Solve on Sudokupad
Solution code: Read left-to-right then top-to-bottom, every water cell not passed through by the roller coaster (only digits, no spaces)
Comments
on 10. October 2024, 03:50 by wisty
Beautiful!!! Super clean and surprising and fun throughout! Thank you so much!
on 13. September 2024, 23:46 by Christounet
Wow ! When an apparently insignificant rule is so powerful that it just builds the whole puzzle ! Masterpiece. Thanks :)
on 25. May 2024, 17:40 by Lucx
Brilliant construction! Chapeau! I had a very tough time in the middle of this puzzle. But it is actually always fair and you „only“ need to find the right rules to be followed to get the next tiny little step. The amount of rules gives you some options, though. Thanks for creating and sharing this one, the cogito!
on 22. January 2024, 12:28 by wpolly
Took more than 2 hours for a solve. The logic involved is hard but brilliant.
on 10. January 2024, 17:54 by astronixia
Absolutely brutal but extremely interesting puzzle. Apart from a couple of stumbles while getting used to the rules, it was a fairly smooth solve for me (slow, but smooth). Even after solving it, its hard to believe this has a unique solution.
on 8. January 2024, 16:24 by Tim Dunkley
Brilliant but brutal. 8.5 hours for me.
on 8. January 2024, 11:00 by madhupt
Stupendous! What a monster of a puzzle! Intricately set and the ruleset actually does give a unique solution is a miracle! No digits in clues, yet it solves. Thanks for sharing this.
on 7. January 2024, 16:24 by samuel1997
Seeing this puzzle from CTC and decided to give this a go due to the peculiar grid, I was speechless of how amazing it is! Definitely one of my favorite puzzle!
on 31. December 2023, 14:38 by Fool on Hill
Great puzzle - kept me busy for a while. Deservedly highly recommended for some wonderful deductions.
on 10. April 2023, 07:58 by RJBlarmo
Absolutely incredible puzzle!
on 17. March 2023, 20:30 by ddx01
Wonderful puzzle, and quite challenging. Thank you, cogito!
on 12. March 2023, 20:25 by Agent
One of the most incredible minimalistic constructions I've ever seen.
on 1. March 2023, 16:35 by Elliptical
Awesome puzzle. It's amazing that it resolves to a unique solution. The solution path is narrow and filled with beautiful gems.
on 28. February 2023, 13:05 by Luigi
In the example every land cell is visited by the loop. Is this a "must"?
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No it's not.
on 27. February 2023, 15:03 by BHUNTER47
Probably the happiest I've ever been with a solve. Amazing.
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I meant to come back and say that comments like this are a big part of why I set puzzles, thanks so much!
on 25. February 2023, 23:45 by Myxo
Beautiful puzzle!
on 25. February 2023, 22:51 by tallcat
Far far outside my comfort zone as a solver, but I enjoyed it immensely. Some fascinating interactions from the ruleset.
on 25. February 2023, 14:53 by kmoter
Very nice, thanks
on 25. February 2023, 10:39 by ONeill
A truly incredible puzzle filled with original logic the whole way through. Great job, and thanks!
on 25. February 2023, 05:06 by polar
Very refreshing puzzle! A great twist on an already awesome genre thanks :)
on 25. February 2023, 04:26 by henrypijames
A perfect, dictionary example of miraculously minimalistic construction of high-complexity sudoku.
on 25. February 2023, 02:51 by Xendari
Great puzzle! Found it very tricky as I'm awful at rollercoaster XD the deductions were quite unique and felt fair once understood
on 25. February 2023, 00:44 by Jesper
Really fun and challenging puzzle, thanks!
on 24. February 2023, 20:28 by KNT
Very fun! Of course it's already been stated, but the fact this sparsely clued grid yields such a variety of nice logic is astounding. One of the best minimalist constructions I have solved.
on 24. February 2023, 19:41 by wooferzfg
This is an incredible puzzle. It's amazing that it has a unique solution, let alone one with so many intriguing steps. Figuring out where to look next can be tough sometimes, but every step is fair and rewarding.
Also, it was really fun to recognize the logical similarities between this puzzle and our Loop Nurikabe puzzle :)
on 24. February 2023, 19:36 by Andrewsarchus
Amazing Puzzle. Very challenging to find some of the the logical deductions needed to solve this puzzle, but when you do, they are absolutely beautiful.
