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 blocks and whatever number I see more of in the board, then lines and columns.
Then give up when I inevitably get it wrong
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.
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.
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.