#630, January 25 - January 31, 2025:
The Weekly 'Unsolvable' Sudoku Puzzle
by Andrew Stuart
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WARNING: This is the Weekly 'Unsolvable' Sudoku, rated above 'Extreme'.
This is currently unsolvable by my solver, except perhaps with trial and error strategies.
Using the solver will not help you. (much).
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Archive
Each week a new 'unsolvable' will be published and the previous will be accessible here from this archive section.
If you like very tough puzzles, these are for you.
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Discussion...
Post an idea here...
... by: Serban
# 630 A1=1 E9=7 H7=6 J9=4 Basics to 27
1. Number 1 n=3 e=6 N=19 Nc=10 Ns=7 => C6=G5=1 solve
2. Number 2 n=2 e=7 N=29 Nc=43 Ns=5 => C5=H3=2 => basics to 41
2a. W-wing 67 [C1,F3] => [E1,F3] <>6 => C1=6 solve
Note: B2=A9=2
3 . Number 8 n=3 e=6 N=23 Nc=24 Ns=21 => A6=G9=8 solve
Note: J5=F7=8
4. Number 9 n=2 e=7 N=31 Nc=52 Ns=50 => F2=E7=9 solve
correction 1. Column 1 n=5 e=4 Nc=3 Ns=3 => G1=5 OR E1=3 OR G2=3 solve
... by: Frans Goosens
#630
Combination
2-Ditgits cells
Total solving time is : 7 sec.
Number of logical steps is : 349
... by: Dieter
#630 - basics: A1=1; H7=6; E9=7; J9=4
strategy: try to get hidden pairs or triplets
A7 = (2,3,8,9)
failed after basic checks : A7=2,8
A7=3 solves with G2=3
Review: G2=3 alone solves.
... by: Serban
# 630 A1=1 E9=7 H7=6 J9=4 Basics to 27
1.Column 1 n=5 e=4 Nc=3 Ns=3 => G1=5 OR E1=3 OR G3=3 solve
2. Number 5 n=3 e=6 N=17 Nc=16 Ns=7 => [ E3 OR H4 ]=5 solve
3. Number 6 n=4 e=5 N=17 Nc=10 Ns=5 => E5=6 solve
4. Number 7 n=4 e=5 N=15 Nc=8 Ns=6 => D3=7 solve
