2 X 4 sudoku

For fans of Killer Sudoku, Samurai Sudoku and other variants

Re: 2 X 4 sudoku

Postby urhegyi » Mon Dec 06, 2021 3:10 pm

What I needed for the hard one were a 2sk(R3C4<>3), an x-wing(R4C3<>3), a disc nice loop(assuming R1C1=2 leads to contradiction, so R1C1<>2=5) and another disc nice loop(assuming R2C7=7 leads to contradiction, so R2C7<>7=5).
Like to see a solver output to compare if it can be done easier.
urhegyi
 
Posts: 612
Joined: 13 April 2020

Re: 2 X 4 sudoku

Postby 1to9only » Tue Dec 07, 2021 3:53 pm

Requires Forcing Chains ED=7.0+:
Code: Select all
5..8...1.37.5...7.....1..2.6.5....3.4.5..5.....3...2.84.8...7..2 ED=7.2/1.2/1.2

Requires Nishio Forcing Chains ED=7.5+:
Code: Select all
..4736.13..6....1......4.4...12..71...4.8......2....2..84.2873.. ED=7.8/1.2/1.2
1to9only
 
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Joined: 04 April 2018

Re: 2 X 4 sudoku

Postby urhegyi » Tue Dec 07, 2021 6:24 pm

Thank you for confirming what I thought. The hard one has a higher rating as the evil one. So the difficulty level used by Isolvepuzzles.com is not always reliable.
Today I solved a medium one and it needed a skyscraper. So the difficulty level is not the one which is used by other sites or newspapers but far above it.
urhegyi
 
Posts: 612
Joined: 13 April 2020

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