SudokuSolver Forum

There are three difficulties to choose from.
All three puzzles have the same solution.

The difficulty levels explained     The ratings explained

A) Novice.
B) Apprentice (mainstream edition).
C) Master (70 Intersection, 4 Naked Pair, 1 EARLY Two String Kite on 2 in g1, 1 Skyscraper on 2 in g2, 2 XY-Wing: one on 9 in g2 and one Intergrid on 3 in g7 and g10). Select to view details.
The advanced techniques are needed in 3-4 different grids.



Regular Clueless Special #45A (Novice)

Rating based on required solving techniques:  Moderate

003000090205076000000030600027000000060000080000000300000001007400200008009703050
000037000000508040008000090200000001010000004007000000004000003000650080023090006
000760800300002000001000020010000005006000000000000410005009001600004030100035042
400008005000000600980001400050000001200000003090000000002700000000000090100000040
000059000000002090019000500370000000020000750008000002600000007200063010050007003
000803090005000200980070000000000004800000030040000000000030050100080070403006900
000500076308004020000008900000000007004000590090000000026000000800050004000007000
087200100000304006000000240600000007900000008000000020020030060500000800094820005
650008000000700420071000900002000000000000302009000600000000040700060230803007000



Regular Clueless Special #45B (Apprentice)

Rating based on required solving techniques:  Tough

003000090205076000000030600027000000060000080000000300000001007400000008009703050
000037000000508040008000090200000001010000004007000000004000003000650080023090006
000760800300002000001000020010000005006000000000000410005009001600004030100035042
400008005000000600980001400050000001200000003090000000002700000000000090100000040
000009000000002090019000500300000000020000750008000002600000007200063010050007003
000803090005000200980070000000000004800000030040000000000000050100080070403006900
000500076308004020000008900000000007004000590090000000026000000800050004000007000
087000100000304006000000240600000007900000008000000020020030000500000800094800005
650008000000700420071000900002000000000000002009000600000300040700060230803007000



Regular Clueless Special #45C (Master)

Rating based on required solving techniques:  Super Hard

003000090005076000000030600027000000060000080000000300000001007400200008009703050
000037000000508040008000090000000001010000004007000000004000003000650080023090006
000760800300002000001000020010000005006000000000000410005009001600004030100035042
400008005000000600980001400050000001200000003090000000002700000000000090100000040
000009000000002090019000500300000000020000750008000002600000007200063010050007003
000803090005000200980070000000000004800000030040000000000000050100080070403006900
000500076308004020000008900000000007004000590090000000026000000800050004000007000
087000100000304006000000240600000007900000008000000020020000000500000800094800005
650008000000000420071000900002000000000000000009000600000300040700060230803007000

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#45c was a particularly good one. It takes a lot of patience, but every move is reasonable. Thanks as always, Børge!

I'm glad you liked it. Especially since it is one of the hardest RCS Master level puzzles, and I was in doubt if I should post it. I spent two days making a small stock of RCE and RCS puzzles, and 2 or 3 of them ended up more difficult than intended. Sorry about that.

Personally I really like RCE #45C and #46C due to the intergrid stuff.
Am I the only that fancies this kind off stuff?

RCE #47C is also a first if its kind. It requires only one advanced technique, which is a Grouped Two String Kite.

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I do indeed enjoy the intergrid moves, though the specific techniques in RCE #45C and #46C are a bit beyond my current abilities, so I'm saving them for when I've advanced further and feel I have a shot at finding them unaided.

This reminds me, there's something I've been meaning to post in the "Gattai Puzzles" section....

EDIT 1:
I have deleted and resubmitted the original entry with some revisions. What I originally wrote was not 100% correct.
EDIT 2:
Also the second time I did not get it 100% correct, so again I have deleted and resubmitted this entry with some revisions. Hopefully, third time correct (not just lucky).

Thanks for the puzzle.
If you also generate Clueless puzzles, and want to post one or more as a regular RCE or RCS, I will happily yield slots. Just send me a PM or preferably an email to one of the following email addresses:
OR

Please don't be so modest.
It definitely seems that you have cured that "seafood allergy" of yours for good. Mastering a puzzle like RCS #45C proves that 100%.

To my knowledge Intergrid Skyscraper and Intergrid Empty Rectangle can only occur in a Clueless Explosion type puzzle, i.e. a puzzle where a clueless 9x9 grid is weaved into other grids as their Center-Dot cells.
If I can find some time, I will under Gattai Techniques try to post "Intergrid Skyscraper Explained" et al. including images, so that this topic finally gets some posts.

Here the rules an Intergrid Skyscraper (in a Clueless Explosion puzzle) must fulfill in addition to the basic Skyscraper rules:

1. One or both Roofs must be in a clueless cell. Otherwise the Skyscraper would only be Intragrid and not Intergrid. This since both Roofs must see all cells where candidates can be eliminated.
2. Both Basements must be in non-clueless cells (in the same row or column).
   
   • If both Basements are in clueless cells, then one of the two towers will have both its Basement and Roof in clueless cells making the tower an Intersection. This since the tower's Basement and Roof have a strong link which implies that one of them must be true. Hence the candidate for which they have a strong link can be eliminated in all other clueless cells in this nonet except in the two cells where the Basement and Roof are.
   • If one of the Basements is in a clueless cell, then 1. dictates that the tower whose Basement is in a clueless cell also has its Roof in a clueless cell, and again since a tower's Basement and Roof have a strong link the tower becomes an Intersection.
   • If both Basements and both Roofs are in clueless cells, then the puzzle has no solution. If you in a nonet have two independent strong links for the same digit, then this digit must occur twice in that nonet.
3. All cells where candidates can be eliminated are clueless cells.

Please note that for an Intergrid Skyscraper the two towers must not necessarily rise in the same direction. One can rise right and one left or one up and one down.

Here the rules an Intergrid Empty Rectangle (in a Clueless Explosion puzzle) must fulfill in addition to the basic Empty Rectangle rules:

1. One of the cells with the strong linked pair of candidates must be in a non-clueless cell.
   If the strong linked pair of candidates both are in clueless cells, they become an intersection. See 2. for Intergrid Skyscraper for details.
2. All cells where candidates can be eliminated are clueless cells.
3. As for a normal Empty Rectangle one of the strong linked cells sees all cells where candidates can be eliminated.
   In the nonet where the Empty Rectangle is, only the clueless cell sees all cells where candidates can be eliminated.

Here the rules Intergrid Remote Pairs in a Clueless Explosion puzzle must fulfill in addition to the basic Remote Pairs rules:

1. At least one of the end cells in the Remote Pairs chain must be in a clueless cell.
2. All cells where candidates can be eliminated are clueless cells.

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Quis custodiet ipsos custodes?

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I'll be happy to post other good puzzles when I stumble into them. I've used JSudoku to generate Cluelesses a few times -- the software finds these much more difficult to generate than "regular" gattai (understandably so), and I haven't gotten one that I felt was truly worthy of being posted yet. But I will certainly let you know if I do.

Your explanation of intergrid skyscrapers/empty rectangles definitely deserves to be the first post in the "gattai techniques" section! And I look forward to a picture or two.

I don't think I'm being falsely modest about my solving capabilities -- for instance, the tricky move in RCE #47c completely eluded me, though I searched for quite a while.

Re seafood: I turned a bit of a corner when I realized that skyscrapers/kites were a visual pattern I could see (rather than the mechanical exercise of saying "cell A has a strong link to cell B, which has a weak link to cell C....") From there, the advanced wings seemed to follow relatively naturally (though it still has taken nearly a year to master them).

The next step is to try to improve on fins, empty rectangles, things of that nature. As for chains, it baffles me that anyone ever actually finds one in a puzzle. But as you pointed out, I used to feel the same way about a simple fish, so....maybe someday.