When you first crack open a new sudoku puzzle, do you look at the rows or columns first? Or do you work in blocks? What’s your strategy?
I start with 1s, look in the row blocks to see if I can fill any, then the column blocks. Then move on the 2s, 3s… If a block or row or column is mostly filled in I see if I can get any of the rest to close it out.
Exact same here
I start with blocks and whatever number I see more of in the board, then lines and columns.
Then give up when I inevitably get it wrong
I start with 1’s and then 2’s and then 3’s, etc. Eventually, you’ll find them all. Just a good way for me to start.
Wait, you start by trying to find anywhere you can place a 1, then once you’ve got those you move to 2’s and so on and so forth? Like… Just looking at the whole board? You don’t break it down and work by sections?
Well, yeah. I have to start somewhere. My Spock brain came up with that.
I… I never even considered that approach. I always start with the 3x3 blocks, figuring out what numbers are missing and where they might fit. If I get stumped working blocks, I move on to rows and then columns last.
Start with a random number, look to see where the rest are in the grid, and look at the columns and rows to see if there are any easy ones to fill in, then move on to the next number.
Then there are a few other algorithms I have to use if the sudoku problem is more challenging. Looking at individual lines to see if there are missing numbers. Try to figure out where numbers absolutely cannot go to narrow things down.
For each number, I mark all cells where I know I can’t put it.
If one block, column or row has only one possible cell where a number can be, I put it there and then update all cells where I now know I can’t put it anymore.
This algorithm probably isn’t the fastest, but it’s easy to do manually and it has the advantage that you don’t need to backtrack.
If you want some tips or are just curious, this channel has a lot of content about sudoku and variants: https://www.youtube.com/channel/UCC-UOdK8-mIjxBQm_ot1T-Q
Not so much looking for tips as I am just seeing what everyone else does. I love sudoku puzzles. I don’t think I’m necessarily good at them, but I do enjoy them on the reg, lol.
Thanks for the link, though! I’ll keep it in mind.
What I usually do is going through the puzzle doing snydernotation first (marking when a number can only be in 2 places in a box)
Most easy puzzles can be done with only that, then when it stops being fruitful I fully mark the puzzle up and start looking for things in roughly this order:
- triples
- x-wings
- simple-fishes (skyscraper, 2-wing kites)
- xy-wings
- xyz-wings
- swordfishes
- chaining techniques
That’s at least my basic rough order of going through solving a puzzle.
That’s… a lot. I’m assuming those are techniques for efficiently solving sudoku puzzles? I never thought about it, but it makes sense that there would be defined methodologies for tackling this kind of puzzle.
Yeah, there are a lot of techniques, mostly they are patterns that are quite easy to spot, so that you don’t have to manually go through the logic each time. Basically on the form of If a number can’t be here then it must be here, can’t be here, and must be there, because of this this one cell that looks like it’s detached from the rest can’t be this. Very difficult to only explain in text, but here is a link to some of the most common ones, if you are interested, with images and examples:
X-wings especially: https://www.sudokuwiki.org/X_Wing_Strategy
general explanation https://www.sudokuwiki.org/Getting_Started look on the left side of the page for different techniques sorted by difficulty.
I also have a been the moderator of r/sudoku for years, where we usually help people out solving puzzles that they can’t solve :) It’s a lot of fun :)
