Sunday Stumper: Anti-Pi Sudoku by Serkan Yürekli

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This year, we have started to have some extra difficult Sunday Stumpers, about once a month. These will be quite tough puzzles, but with a logical path to be found (and solution videos to help). This second Sunday Stumper is a challenging Sudoku variation with a special theme for Pi Day, whether you like Pi or are in the Anti-Pi = Tau camp.

Anti-Pi Sudoku by Serkan Yürekli


or solve online (using our beta test of Penpa-Edit tools)

Theme: Pinenut

Author/Opus: This is the 320th puzzle from our managing editor Serkan Yürekli.

Rules: Standard Sudoku rules. Also, no two of 3, 1, and 4 can appear in adjacent cells. Some cages are marked by dashed lines; the sum of the digits in each cage must equal the value given in the upper-left corner of that cage (digits cannot repeat inside a cage). Some arrows given outside the grid indicate the sum of the digits along that diagonal path (digits can repeat on a diagonal). The value of any ungiven sum in either a cage or an arrow must not be a number composed solely of the digits 3, 1, and 4 (like 4, 11, 14, 31).

Difficulty: 5 stars

Time Standards (highlight to view): Grandmaster = 28:00, Master = 1:00:00, Expert = 2:00:00

Solution: PDF; a solution video is also available here from Dr. Sudoku and another video here from Cracking the Cryptic.

Note: Follow this link for other variations on Sudoku.

  • carpenter says:

    Sudoku isn’t my strong point, but I think this might be the hardest puzzle to have appeared on this blog. Lots of very tricky (& cool!) deductions.

  • Freddie Hand says:

    Pretty sure that Quintessence is considerably harder than this.

    • drsudoku says:

      Agree that Quintessence is the hardest challenge we’ve posted, at least from my direct experience. We did not put par times on Quintessence though except to warn GM times > 2h. Of the puzzles with complete median standards, I believe the highest median time (1h30m for Master) standard we’ve had was for this Gapped Kakuro by Serkan. There are many giant (book / patron) puzzles that score higher on difficulty but not routine for the website. And having this high a time for a 9×9 sudoku is unusual. But the Sunday Stumpers are an experiment and we’re curious if you all enjoy or dislike these different puzzles from time to time.

  • carpenter says:

    Quintessence took me less time, but Sudoku is one of my worst puzzle types. If I try to think about it “objectively”, Quintessence does seem quite a bit harder (for one thing, it’s a lot bigger).

    So far I’m loving the Sunday Stumpers. About once a month feels like a good frequency, rare enough to make every puzzle feel special.

  • skynet says:

    That was brutal. I am piqued by how the demarcations between GM/Master/Expert times become more pronounced as the difficulty becomes higher.

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