![]() ![]() Josh describes his yearlong journey from being a bright, nerdy, but otherwise normal guy living in his parent’s basement to being a finalist in the U.S. It can be viewed that way, but the book is actually an interesting piece of investigative science journalism combined with a memoir, that just happens to offer some useful techniques for remembering things. If this describes you, I think you’ll like the new book by Joshua Foer called Moonwalking with Einstein: The Art and Science of Remembering Everythingįrom the first few Amazon user reviews, you might be inclined to believe this is a self-help book for improving your memory. I know from your correspondence that many of you download my puzzles to keep your brains active and sharp. You can use the same type of logic to find a 2. So I an eliminate 1 from other squares on row 4. Now, looking at the center block, I can see that 1 must occur in that block in row 4. That means we can eliminate 1 from all the other squares in that column. Looking at the block on the lower left, I can see that the 1 in that block must occur in the first column. I’m gonna use the row/block and column/block technique to narrow them down further. Looking at just the 1s, these appear to be possible squares for ones: Here’s the puzzle at the point Margaret got stuck. If you’d like to try your hand at this puzzle, you’ll find the original here. Our first puzzle is from Margaret, who got stuck solving the daily Challenging puzzle from May 12th. If you want help with a particular Krazydad puzzle (especially puzzles that are easier than “Super Tough”), drop me a note, and I’ll troubleshoot your problem too! I’ve decided to devote the next few blog entries to puzzle solving techniques. Occasionally, I get mail from fans of the site who need help with a puzzle. | Comments Off on Sudoku Troubleshooter #2 – XY-Wing Of course this is contingent upon there only being one possible solution… Looking at column B, assume B4 is a 9, then A5, A9, B5 and B9 all have the same possibilities and there would be two possible solutions ergo B4 is not a 9 but a 2 and away you go. UPDATE: Stephen wrote me with an alternate breakthrough which makes use of the knowledge that the puzzle must have only one solution: In book 40 alone, puzzles 2,3 and 4 make use of it. Now the rest of the puzzle solves easily.Īs it turns out, XY-Wing crops up pretty frequently in the Tough puzzles. ![]() Once we’ve cleared the 1s out, it’s obvious that D3 must be 8. This means we can clear 1 as a possibility from cells D3, and E5.īoth of these cells are connected to both E4 and D5. This means that any cell that is simultaneously connected to both E4 and D5 cannot ever be 1 (because it would prevent both E4 and D5 from being 1). Since E4 can only be 2 or 7, either E4 or D5 must be 1. Think about the ramifications: If E4 is 2, then D5 must be 1. It is connected to cell E3 (which can be 1 or 7) and cell D5 (which can be 1 or 2). The root of the XY-wing is cell E4, which has 2 and 7 as possibilities. You can read about the XY-wing technique here. It turns out there is an XY-wing lurking in there. Normally, I’d be tempted to just substitute in a value and see what happens, but there is a more logical way to approach it. It looks nearly done, but the remaining cells look nearly intractable. Here’s the puzzle at the point where Margaret got stuck. This puzzle is also from Margaret, who got stuck on a Tough puzzle (Tough #4 from book 40). If you are stuck on a particular Krazydad puzzle, drop me a note, and I’ll use this space to help you out. ![]() This is part of a series on puzzle solving techniques.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |