Double Dutch Sudoku Advent (12) - Position vs. Quad Sums
(Published on 12. December 2014, 12:00 by Eisbär)
Richard and I have created a fresh sudoku advent calendar in which we combine a well known variant with a relatively unknown variant every day. Combining variants leads to interesting and surprising new solving techniques.
Logically solvable
All puzzles can be solved completely logically although the logic is sometimes well hidden and is inherent to the combination of restrictions that the different types offer. For that reason we have written some solving hints for most of the puzzles, published in a very tiny font. If you want to read the hints, simply copy these in a text editor and enlarge the font size.
Position
Place the digits from 1 to 9 in every row, column and 3x3-block. Numbers outside the grid indicate the position of the largest digit in the first three cells.
Quad Sums
A circle at a corner implies that one digit is the sum of the remaining three digits at that corner.
Solving hints
9 in block middle-bottom in R7C456
9 in block bottom left not included in Quad Sum; Quad sum in R78C12 needs a 1.
The two quad sums in block middle bottom also need a 1. Quad sum in R78C89 = {2349}
9 in R8C9
R7C8 = 3/4; R8C8 = 2/3; R9C8 = 1; no 8 in R78C7; R9C7 = 7/8
8 in block bottom right locked in R9C79. :=> 8 in block middle bottom is part of a quad sum and it must be the other sum then the sum with 9. :=> R7C5 not 9
R78C5 not 8
Sum of 9 in block middle bottom can’t be formed with 2/3/4 since there is no possibility for the quad sum in R78C12. So both 9 and 8 need a 1. 1 in R8C5. R7C5 minimal 3, so 6 and 7 in block are not part of a quad sum. :=> R9C46 is pair {67}
R9C9 = 5; R78C7 = pair {67};
R7C46 = pair {89}
R8C2 = 8; R9C2 = 9
R8C3 = 7; R7C3 = 6
Quad sum in R78C12 = {1258}; R9C5 = 2; R7C5 = 3
Solution code: Row 4, followed by Column 6
Comments
on 27. June 2017, 00:17 by ibag
Danke, LG zurück!
on 26. June 2017, 20:13 by Saskia
ibag: Was fuer ein schoener Abschluss des Abends :) LG aus Norwegen
on 26. June 2017, 19:37 by ibag
Gut, dann wird der Kommentar gleich wieder versteckt. ;-)
on 26. June 2017, 16:25 by Saskia
ibag: Jaaaaa :-D Hurra. Herzlichen Dank!! Freu huepf ...
on 12. December 2014, 18:03 by Statistica
Oh dear you're right. It is the reason that I felt the whole day that something was missing... :-)
on 12. December 2014, 17:45 by CHalb
Eisbär, I was aware of this special situation and was looking forward to how you two might not make it happen ;-).
on 12. December 2014, 16:49 by Eisbär
Next week it will be business as usual I guess :-)))
on 12. December 2014, 16:48 by Eisbär
I just realized something... it's an honour to generate this puzzle today on 12.00!
This is the first time since 30 October 2009 that there isn't a puzzle of my good friend Richard published on Friday's at 12.00... :-D
