Even Corners (nearly)
(Published on 30. December 2024, 23:21 by pagedo)
16 even corner squares makes the sudoku impossible to solve. So 14 even corner squares is the best we can do for a solvable sudoku.
Normal sudoku rules apply.
Cells with grey squares contain even digits.
Cells joined by an X sum to 10. Not all Xs are given.
Cells joined by a white dot are consecutive. Cells joined by a black dot have a ratio of 2. Not all dots are given.
Link to sudokupad
Link to Odd Corners
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Hope you enjoy it. Feel free to give feedback.
Thanks
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Solution code: Digits in row 2
Comments
on 7. January 2025, 12:38 by Slumped_5
@MattConco, once you've coloured odds and evens, some additional colouring should get you through, choosing the right cell is the key here, NO NEED of bifurcation.
on 3. January 2025, 20:00 by MattConco
28mins - Managed to colour the entire grid and then reduced quite a lot of cells down to pairs but couldn't see the last step to unravel. I tried to bifurcate and ended up correctly guessing and solving. Unless Im blind, seems like harder than 1 star logic to unwind.
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MattConco - I just ran through again and below should get you there
SPOILER:
Starting Point
Pencil marking everything and also corner marking 5s R8C2, R8C3, R7C7 and R7C9 it resolves to odd cells 13579 (18 cells), 1379 (22), 5 (2), 13 (2) or even cells 2468 (33 cells), 26 (2), except 2 mixed cells 37, 46.
Simple
remove invalid candidates 19 from R4C8
Next
R8C4 37 cell removes 37X37 from R8C6 R8C7 X sum. Clean up and a 28 cell will do similar to another X sum.
Next
if not done, C5 13 pair will clean grid box 5 which should give digits for the col 3/row 7 X sums. Everything will unfold from there
on 1. January 2025, 03:56 by PinkNickels
Happy New Year!
on 31. December 2024, 22:07 by SanFranSam
Sweet little puzzle. actually got done in less than 20 minutes. Watching CTC really helped.
on 31. December 2024, 20:13 by Archon
Great fun, thank you!
on 31. December 2024, 15:45 by GeorgeTheToad2
Nicely done. Thank you.
on 31. December 2024, 07:45 by softie
This one was quite a bit easier than Odd Corners, but I appreciated that even though there were some interesting Phistomefel facts to discover, I actually did not use that at all in solving the puzzle. No secrets, just clean parity logic to follow.
on 31. December 2024, 07:41 by Decapod
I'll offer validation to anybody else who sees the previous comments and doesn't think the puzzle is that easy. Yes, within 6 minutes I had determined the parity (even/odd) of every cell and placed 5 digits in the grid, but then it took me quite a while to find the "2nd break-in" that solved the rest of the puzzle! Final time was just under 30 minutes.
on 31. December 2024, 01:38 by pagedo
Added link to Odd Corners
on 31. December 2024, 00:39 by hardline35
Very nice puzzle! My time is exactly even 10:00 minutes!
on 30. December 2024, 23:52 by Steven666v2
15:37. I like a parity puzzle!
on 30. December 2024, 23:48 by sujoyku
Thank you for this nice parity puzzle, pagedo! It was approachable and fun to solve.
