Phantom Killer 6x6
(Published on 4. May 2020, 02:01 by Mondestrunken)
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As in a standard 6x6 sudoku, no block, row or column may contain a duplicate of any number from 1-6. The sum of the digits in a cage corresponds to the number in the corner. Numbers can repeat in a cage (but not in a block, row or column).
Some cells are blank; they once held numbers that completed the sudoku in a standard way. The number at the end of a row or column in a white cell indicate how many cells in that row or column contain numbers. The number at the end of a row or column in a grey cell indicate the longest chain of consecutive cells containing a number in that row or column. E.G.:
Solution code: The third and fourth rows of the Sudoku, left to right (use * for blank cells)
Comments
on 11. April 2023, 07:08 by zrbakhtiar
penpa+: https://tinyurl.com/227c6fpf
on 6. May 2020, 12:31 by zhergan
Very nice one. Thanks:) Looking forward to see the bigger version..
on 4. May 2020, 22:39 by Mondestrunken
@sfumato: already working on one!
on 4. May 2020, 20:53 by sfumato
@Mondestrunken: Thanks for the clarification. I really like that there are a few ways to approach this! Hoping to see a 9x9 version of this in the future :D
on 4. May 2020, 20:00 by Mondestrunken
@sfumato: There are places where you can use the fact to help you along - the method I have in mind to solve it uses it several times, including right at the beginning! :) But yes, where it is most crucial is in solving the possible ambiguity at the end! Glad to have been able to clear it up though!
on 4. May 2020, 19:30 by Mondestrunken
@sfumato: that is the correct solution (and I have checked, the solution code works with it) - if you meant the 1 and the 5 in the cage being switched around, it is because of the rule cited below - the rest of the original sudoku that has been modified would not work (in other words, a number that would have been in a blank square makes the other way round impossible).
on 4. May 2020, 12:26 by Mondestrunken
@zhergan: hopefully this should all clarify the possible ambiguities! :)
on 4. May 2020, 12:24 by Mondestrunken
Corrected a mistake in the example phantom sudoku (!) :)
on 4. May 2020, 12:18 by Mondestrunken
@marcmees - my mistake - a stupid error
on 4. May 2020, 10:07 by Mondestrunken
Reformatted the rules so as to clarify them.
on 4. May 2020, 10:01 by Mondestrunken
@Puzzle_Maestro @zhergan: The rule that is important here is that the blank cells have been removed from a fully functioning sudoku - figuring out what the blanks cells have to have been is imperative in clearing up this ambiguity. c.f. "Some cells are blank; they once held numbers that completed the sudoku in a standard way." :)
on 4. May 2020, 07:48 by Puzzle_Maestro
I initially missed the rule that numbers can repeat in cages: I think you should make this rule bold as it is unusual.
