9 votes

How to solve a blank Sudoku grid (surrounded by 28s)

6 comments

  1. [4]
    Wes
    (edited )
    Link
    I enjoyed the last video posted from this channel, and I'm enjoying this one, too. Does anyone know the specific notation he uses for marking possible numbers? Sometimes it's in the top-left...

    I enjoyed the last video posted from this channel, and I'm enjoying this one, too.

    Does anyone know the specific notation he uses for marking possible numbers? Sometimes it's in the top-left corner, sometimes the center, and rarely in the top-right corner.

    edit: I'm thinking the top-left corner numbers are solving via "regular sudoku rules", and the middle numbers are solving by summation.

    2 votes
    1. [3]
      Apos
      Link Parent
      When he marks in the corners (any corners), it means the number can be there, but other numbers that aren't marked could also be there. When he figures out exactly which numbers go in a square, he...

      When he marks in the corners (any corners), it means the number can be there, but other numbers that aren't marked could also be there. When he figures out exactly which numbers go in a square, he erases the corner markings and does center markings. At that point nothing else can go there but those ones. Sometimes he'll add corner markings with center markings. This is to add an extra emphasis on that number so that he can spot it faster later. (Sometimes though it's because he forgets to clean up the corner markings.)

      5 votes
      1. cfabbro
        (edited )
        Link Parent
        Well said. Or as a shorthand, you can basically think of the corner marks as "can be" (not exclusive), and the central marks as "can only be" (exclusive). And also something worth noting (which...

        Well said. Or as a shorthand, you can basically think of the corner marks as "can be" (not exclusive), and the central marks as "can only be" (exclusive).

        And also something worth noting (which might be where some of the confusion is coming from), is in their software the corner marks get moved around to remain in ascending order. So if there is only a 9 corner mark, it'll be in the top left of the cell. But if he then adds a 1, 2 and 4 corner mark to that same cell, the 1 will go top left, 2 top right, 4 bottom left, and 9 will move to bottom right. And in the rare cases where there is more than four digits corner marked, the top middle, then bottom middle positions will open up as the next positions.

        To see it in action, you can experiment with their system on this very puzzle, with the link they provide in the video description: https://app.crackingthecryptic.com/sudoku/qTJppjtp3b

        3 votes
      2. Wes
        Link Parent
        Thank you, that makes sense! I find his ability to process so quickly extremely impressive. There's clearly very strong pattern recognition for him to be able to fill via regular sudoku rules...

        Thank you, that makes sense!

        I find his ability to process so quickly extremely impressive. There's clearly very strong pattern recognition for him to be able to fill via regular sudoku rules almost by reflex. (Can take me hours)

        3 votes
  2. cfabbro
    Link
    Puzzle solving doesn't start until 4min 20sec. So for those on mobile (where linked timestamps often don't work very well), be sure to skip ahead.

    Puzzle solving doesn't start until 4min 20sec. So for those on mobile (where linked timestamps often don't work very well), be sure to skip ahead.

    1 vote
  3. nothis
    Link
    I remember this guy from the miracle sudoku! What feels a bit bait-and-switch is that all these aren't proper sudokus but have extra rules that basically just make them ordinary-hard-sudoku levels...

    I remember this guy from the miracle sudoku!

    What feels a bit bait-and-switch is that all these aren't proper sudokus but have extra rules that basically just make them ordinary-hard-sudoku levels of hard, it's just new rules! I find new rules more entertaining than just doing ordinary sudokus but it's not really "almost impossible" or anything, it's just a different kind of puzzle.

    1 vote