Dr. Sudoku Prescribes #71 – Cave (Product)

Cave by Thomas Snyder


or solve online (using our beta test of Penpa-Edit tools; use tab to shift between shading mode and the linex mode where left click+drag draws lines and right click marks X’s)

This is a “Franken-Friday” puzzle variation.

Theme: Common Products

Rules: Variation of Cave rules. Each clue represents the product of the # of row cells visible (including the cell itself) with the # of column cells visible (including the cell itself).

Answer String: Enter the length in cells of each of the cave segments from left to right for the marked rows, starting at the top. Separate each row’s entry with a comma.

Time Standards (highlight to view): Grandmaster = 3:00, Master = 4:45, Expert = 9:30

Solution: PDF

Note: Follow this link for other classic Caves. If you are new to this puzzle type, here are our easiest Cave Puzzles to get started on.

  • Jack Bross says:

    Fun puzzle. Pretty easy getting started, but there are a few interesting twists (“How is this going to be unique/resolved? Ohhh…”) and nice use of connectivity in the latter half of the solve*. Given the lack of primes, there was less ambiguity along the way than I expected.

    *There was an essay in the NY Times this week about turning verbs into nouns, and they mentioned “solve”, but not in this context. I actually think that in puzzling, “solve”, meaning the logical process of working through the puzzle, as opposed to “solution”, which is what the process spits out at the end, is a legitimate bit of useful jargon.

  • Anuraag Sahay says:

    I can see the no enclosed white cells constraint dominating today’s example.

  • Anuraag Sahay says:

    Not sure about the theme.Common products? If it means “common products”,you have to be a little more elaborate. But if it means “the products are common” , I dont think so.All products upto 100 are common and factorizable comfortably.

    • LorenR says:

      I think that he means common in the sense that 6, 8, 9 and 12 appear frequently. Maybe there is a deeper meaning as well.

      • Avatar photo drsudoku says:

        The X symbol in the middle with all the repeated 6/8/9/12 clues is indeed the primary part of the theme.

        • Anuraag Sahay says:

          Nice theme from a solver’s standpoint, after its revealed.I can relate this to the experience I had in the middle of the grid.I wouldnt have seen the theme you wanted to be noticed( and I didnt despite it was mentioned) if it was not mentioned. Probably It was misphrased .’Repeated products’ would have sounded much better.

  • Arren says:

    I really enjoyed this one. Although I feel I may have taken a shortcut by finding an area that had to be filled in a particular way in order for the solution to be unique early on.

    And I definitely liked the use of “Common Products”, it provided a significantly different solving path then a standard cave.

  • skynet says:

    1 ‘ 3″

    Calm down folks.Thats 1 hour 3 mins .First 23 mins i was proceeding very slowly not sure how to start or what to do.Then i got the idea of writing the possible pairs that on multiplication leads to the clue and wrote them inside the cell.After that too it was not easy.Still my mind was missing something.
    Then the doctor’s spirit into me moment came and i remembered the lovely little rule”NO CHECKERBOARD “.
    AVOID THE DEADLY CHECKERBOARD .The doctor;s words went into my ears which strangely did not happen earlier. This rule basically held my hand and helped me to complete the puzzle.This lovely rule i used almost till the end.
    Beautiful beautiful puzzle motris!!!!!!!
    Fun level : 10
    Difficulty level : 10
    Ah the moment i got that anticheckerboard rule in my mind it was so good.Finally i got that jubilant feeling of completing the puzzle after battling with it.
    Now i will never forget the checkerboard rule.

  • chaotic_iak says:

    02:31. Heh, not counting answer key extraction time because of an earlier comment.

    Definitely fun to solve. I think I got somewhat lucky for noticing the opening quickly (but then, that certain 6 is pretty crowded already). Afterwards, mostly connecting “outside” cells to, well, the outside, no checkerboard rule, and marking everything that I can at any time clears the puzzle. Not terribly tough for a Friday, but still packs a sufficient amount of difficulty.

    Also, the theme is easy to miss (I originally searched “where that 4 is paired with? It’s common products right” before seeing that only the central X has the property. 😛 ) But it’s a pretty nice one. Still, I’m hoping that each number appears in pairs, not only the middle eight numbers, to make the theme stronger. But heh, not a concern.

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