Space Oddity - Irregular Parity Galaxy Killer Sudoku
(Published on 20. August 2020, 11:18 by Yohann)
Standard irregular sudoku rules apply: each row/column/region must contain all digits from 1 to 9.
Each dot is the center of a point-symmetrical galaxy that behaves like a killer cage. Digits can't repeat inside a galaxy, and the digits in the galaxy must add up to the number next to the dot. E (respectively O) means that the sum is an even (respectively odd) number.
Two symmetrical cells within a galaxy must have different parities, and cells with the same parity within a galaxy must form a single group of orthogonally adjacent cells.
Single-cell galaxies are not allowed. In contrary to a classical galaxy puzzle, not every cell in the grid has to be part of a galaxy.
Solution code: Row 2, Row 8
Comments
on 30. September 2023, 10:09 by puzzeenjoyer
I didn't have to build one of the galaxies, not sure if I made a lucky error or if this was intended. Nevertheless, I very much enjoyed the solve.
on 27. August 2020, 12:37 by SquaringSquirrel
Great puzzle, thanks Yohann! Nice solving path, equally hard from beginning to the end. Rules work well together.
@henry: marking parity with letters worked nicely for me, doesn't mess with other colouring/pencilmarks
on 21. August 2020, 17:00 by henrypijames
How do you color-mark galaxy and parity at the same time? You can't (except with something like shaded colors which brings its own problems). Blanketing the grid with 13579 and 2468 makes things so cluttered that I made several mistakes due to inability to see clearly. So I started over using digits 1 and 2 as parity marker (and color as galaxy market), filled most of the grid with both parity and galaxy, then converted the 1s and 2s into pencilmarks for the solve.
Still had to bifurcated at one point. The false path wasn't too long, but definitely longer than I could test in my head.
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You can draw galaxies with lines instead of coloring them.
No need for bifurcation in this puzzle, you may have missed some logic
Reply: 100% of the time when I bifurcate, I assume it's not necessary, but because I'm missing something. So when I say I had to bifurcate, I mean just that: *I* had to.
on 20. August 2020, 14:34 by marcmees
very nice galaxy .... challenging, but the rule restrictions work nicely together to follow a straight solving path. thanks for the puzzle.
