#700, May 30 - June 5, 2026:
The Weekly 'Unsolvable' Sudoku Puzzle
by Richard Kröger, guest compiler
|
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).
|
Changes March 2026
Due to the introduction of
Forcing Nets many Weekly Unsolvable puzzles can now
be solved. I have flagged all the Sudoku ones which are solvable. I am struggling to make any new ones so we'll
have to see if the Weekly can continue. The point of the Weekly was to provoke discussion and new ideas, so
that is progress. But my solution is unlikely to be optimal so alternatives are welcome.
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.
Share and Enjoy
Supporter Members have access to all these puzzles going back to number 1.
Discussion...
Post an idea here...
... by: Dieter
#700 - initially populated cells: 21 = 25,9 %
No solver used, solver = brain.
basics: F5/F8 = 3/5 or 5/3
populated cells: 21 = 25,9 %
Start with F8=3 and try to build hidden quadruples in row 1:
4 possible cells for #1 = A1, A2, A3 and A9
After basic checks F8=3 and A1=1 get most cells populated.
F8=3 & A1=1 solve with E7=2.
Optimization:
E7=2 & F8=3 solve.
... by: Frans Goosens
#700
Combination 2-digits cells
B8=7 No solution, Undo calculation
B8=8 No solution, Undo calculation
F5=3 No solution, Undo calculation
F5=5 ( E5=6 ) Solved,
Total solving time is : 17 sec.
Number of logical steps is : 2444
... by: Serban
# 700 Basics to 21
1. A8 = H2 = 2 solve
2. G1 = E8 = 5 OR G1=F5=5 solve
3. A9 = E5 = 6 solve
