remedial Sudoko
July 3, 2023 5:35 PM Subscribe
I’m embarrassed to admit I can’t get past the “easy” Sudokus in the NYTimes! Help? What’s the best source to learn the strategies so I can crack a medium? I can do the easies in 6-9 minutes but flop at the mediums.
I’ve been enjoying the mediums with Auto Candidate Mode turned on — it automatically shows you all possible valid options for each square. (I don’t consider that cheating because it’s l information I already have and could document for myself if I wanted to take the time.)
That will show some obvious answers (squares that have only one possibility) and make it easy to see some less obvious ones (a number that’s only valid on one square across a row or column or section).
In addition to that, the insight / strategy I came up with that makes mediums solvable is to look for the same grouping of two or three possibilities across a row or a column or a section. If there are three squares that are, say, “4 6 7”, “4 6”, and “4 7”, then all three of those numbers have to be used by those squares and you can eliminate any 4s or 6s or 7s that show up as candidates anywhere else in that row / column / section.
I can do a medium in 10-15 min with this approach.
posted by sesquipedalia at 6:26 PM on July 3, 2023 [4 favorites]
That will show some obvious answers (squares that have only one possibility) and make it easy to see some less obvious ones (a number that’s only valid on one square across a row or column or section).
In addition to that, the insight / strategy I came up with that makes mediums solvable is to look for the same grouping of two or three possibilities across a row or a column or a section. If there are three squares that are, say, “4 6 7”, “4 6”, and “4 7”, then all three of those numbers have to be used by those squares and you can eliminate any 4s or 6s or 7s that show up as candidates anywhere else in that row / column / section.
I can do a medium in 10-15 min with this approach.
posted by sesquipedalia at 6:26 PM on July 3, 2023 [4 favorites]
Good Sudoku is my go-to sudoku app (on iOS). It's built to be a learning tool for the game and did a good job for me.
It teaches you patterns that you can use to eliminate options and it lets you practice those exact situations, so you can recognize them in the wild.
posted by Mad_Carew at 7:04 PM on July 3, 2023 [11 favorites]
It teaches you patterns that you can use to eliminate options and it lets you practice those exact situations, so you can recognize them in the wild.
posted by Mad_Carew at 7:04 PM on July 3, 2023 [11 favorites]
Don’t use Auto Candidate Mode. That’s doing the work for you, which means you’ll never actually learn it yourself - like using Google Translate to learn French. Instead, use regular Candidate Mode, and go through each cell in the puzzle and mark all the possibilities for that cel. While you’re doing so, think about the patterns sesquipedalia mentioned: two cells with only two possibilities, three cells with some combination of three possibilities, etc.
If you really want to get better, you can approach it from the opposite way and mark all nine candidates in all 81 cells, then go through each one and un-mark the ones that aren’t possible.
Also don’t bother with medium and just go straight to hard. It’ll be, well, hard. But you’ll have to learn, and then mediums will seem easy by comparison. I don’t even attempt the medium puzzle until I’ve solved the hard one, which, humblebrag, I can do in around 10 minutes after using the above method for a while.
posted by kevinbelt at 7:14 PM on July 3, 2023 [2 favorites]
If you really want to get better, you can approach it from the opposite way and mark all nine candidates in all 81 cells, then go through each one and un-mark the ones that aren’t possible.
Also don’t bother with medium and just go straight to hard. It’ll be, well, hard. But you’ll have to learn, and then mediums will seem easy by comparison. I don’t even attempt the medium puzzle until I’ve solved the hard one, which, humblebrag, I can do in around 10 minutes after using the above method for a while.
posted by kevinbelt at 7:14 PM on July 3, 2023 [2 favorites]
In addition to the Auto Candidate mode not really teaching you the logic behind sudoku, it's not really complete. E.g. I just tried their solver and it missed removing some options that were constrained by other squares in that box.
I learned a lot of sudoku strategy by overdosing on the YouTube channel Cracking the Cryptic towards the end of 2020 and beginning of 2021. They don't so much do standard sudoku, but I've learned a lot about different solving logic from a nice British man with a soothing voice who likes REM and has a very predictable set of verbal tics. If that sounds like it would speak to you I recommend it!
I also like Sudoku Wiki's solver as a deep dive on strategy: https://www.sudokuwiki.org/sudoku.htm. You can input an arbitrary puzzle and get a step-by-step walkthrough of the solver's solve path.
Happy solving!
posted by HtotheH at 7:59 PM on July 3, 2023 [2 favorites]
I learned a lot of sudoku strategy by overdosing on the YouTube channel Cracking the Cryptic towards the end of 2020 and beginning of 2021. They don't so much do standard sudoku, but I've learned a lot about different solving logic from a nice British man with a soothing voice who likes REM and has a very predictable set of verbal tics. If that sounds like it would speak to you I recommend it!
I also like Sudoku Wiki's solver as a deep dive on strategy: https://www.sudokuwiki.org/sudoku.htm. You can input an arbitrary puzzle and get a step-by-step walkthrough of the solver's solve path.
Happy solving!
posted by HtotheH at 7:59 PM on July 3, 2023 [2 favorites]
In addition to the Auto Candidate mode not really teaching you the logic behind sudoku, it's not really complete. E.g. I just tried their solver and it missed removing some options that were constrained by other squares in that box.
Yeah, Auto Candidate doesn't do this level of logic, only the first step of checking against the squares in the row, column, and box. It can still be helpful. I found it helpful as a kind of stepping stone. What is more helpful is Auto Check. It keeps me from going so far down a wrong path that I can't find my way out again, though it is useful for me to know that "reset puzzle" is an option. Sometimes I just get too confused and it's best to start over.
Still, what got me, just in recent weeks, from "dork noodling around making all the mistakes" to "someone who can do easy and medium puzzles without a single mistake (on a very good day) and not completely bollox up the hard ones" is that I found a new strategy for filling in the candidates.
I used to go square by square, asking, "Could a 1 be here? a 2? a 3?" etc. I would fill in all the candidates for that box, and then move on to the next box.
Then one day I started going through the whole puzzle number-by-number. That is, starting with 1, and working through the whole puzzle filling in all the places where 1 is a candidate; then doing the same with 2; etc. I make an order of magnitude fewer mistakes with this method. This may be obvious to long-time skilled Sudoku solvers, but it was a revelation to me.
When I'm done, I can see any boxes with only one option, and look at rows and columns and squares to see if there are any numbers that only appear once. Then I can look around for pairs, like 4 & 6 as the only option in two boxes in one row, and removes those numbers from the rest of the relevant boxes. On an Easy puzzle, some boxes will become obvious as I work through the digits; on a Medium, I can have this really fun thing happen where I get all my candidates placed without any errors, and then once I start filling in boxes, they all go down like dominoes; on a Hard puzzle, I will sometimes get to a point where every unfilled box is down to two options, and there's nothing I can find that forces a choice, and I just have pick one and hope it's right. If it's not, I'm not above using the "undo" button.
My new method sometimes feels so mechanical as to not even be challenging on easy and some medium puzzles. But it brings the hard puzzles within reach. And I'm not sure there's a non-methodical way to solve Sudokus, but I'd love to hear other people talk about their strategies. I could be wrong.
posted by Well I never at 10:21 PM on July 3, 2023 [1 favorite]
Yeah, Auto Candidate doesn't do this level of logic, only the first step of checking against the squares in the row, column, and box. It can still be helpful. I found it helpful as a kind of stepping stone. What is more helpful is Auto Check. It keeps me from going so far down a wrong path that I can't find my way out again, though it is useful for me to know that "reset puzzle" is an option. Sometimes I just get too confused and it's best to start over.
Still, what got me, just in recent weeks, from "dork noodling around making all the mistakes" to "someone who can do easy and medium puzzles without a single mistake (on a very good day) and not completely bollox up the hard ones" is that I found a new strategy for filling in the candidates.
I used to go square by square, asking, "Could a 1 be here? a 2? a 3?" etc. I would fill in all the candidates for that box, and then move on to the next box.
Then one day I started going through the whole puzzle number-by-number. That is, starting with 1, and working through the whole puzzle filling in all the places where 1 is a candidate; then doing the same with 2; etc. I make an order of magnitude fewer mistakes with this method. This may be obvious to long-time skilled Sudoku solvers, but it was a revelation to me.
When I'm done, I can see any boxes with only one option, and look at rows and columns and squares to see if there are any numbers that only appear once. Then I can look around for pairs, like 4 & 6 as the only option in two boxes in one row, and removes those numbers from the rest of the relevant boxes. On an Easy puzzle, some boxes will become obvious as I work through the digits; on a Medium, I can have this really fun thing happen where I get all my candidates placed without any errors, and then once I start filling in boxes, they all go down like dominoes; on a Hard puzzle, I will sometimes get to a point where every unfilled box is down to two options, and there's nothing I can find that forces a choice, and I just have pick one and hope it's right. If it's not, I'm not above using the "undo" button.
My new method sometimes feels so mechanical as to not even be challenging on easy and some medium puzzles. But it brings the hard puzzles within reach. And I'm not sure there's a non-methodical way to solve Sudokus, but I'd love to hear other people talk about their strategies. I could be wrong.
posted by Well I never at 10:21 PM on July 3, 2023 [1 favorite]
+1 for cracking the cryptic, as well as their videos (more "classic" sudoku if you look further back) they have apps for Android/iOS/steam that have wonderful hand-made (rather than computer-generated like in the newspapers) puzzles. There is a standalone classic app that has puzzles of various difficulties.
posted by gregjones at 11:05 PM on July 3, 2023 [2 favorites]
posted by gregjones at 11:05 PM on July 3, 2023 [2 favorites]
I'm a big fan of this free website: https://www.sudokuslam.com/
The hints are great, clearly showing the technique you need to use and explaining why, rather than just randomly shoving numbers in, this way you learn the techniques.
posted by chrispy108 at 12:22 AM on July 4, 2023 [2 favorites]
The hints are great, clearly showing the technique you need to use and explaining why, rather than just randomly shoving numbers in, this way you learn the techniques.
posted by chrispy108 at 12:22 AM on July 4, 2023 [2 favorites]
You might also try the hard puzzle. Sometimes it seems easier than the medium version.
posted by SandiBeech at 6:08 AM on July 4, 2023 [1 favorite]
posted by SandiBeech at 6:08 AM on July 4, 2023 [1 favorite]
Best answer: The front matter of this book contains a well written overview of the strategies of Sudoku solving. I recommend both the front matter and all the puzzles. I understand the book to be from the people invented the game? The first 100 are "easy" and they progress to "very hard." I found mine in a Goodwill for $0.50. The previous owner have given up after the second puzzle. Guess they didn't read the front matter!
Personally, I appreciate the paper and pencil approach, but I can see how others would not like that. I rarely write in the possibilities for a square which gets messy with paper and pencil.
posted by AbelMelveny at 6:12 AM on July 4, 2023
Personally, I appreciate the paper and pencil approach, but I can see how others would not like that. I rarely write in the possibilities for a square which gets messy with paper and pencil.
posted by AbelMelveny at 6:12 AM on July 4, 2023
I should add that I played sudoku casually (a few NYT books on the bedside table, fairly regular newspaper attempts) and the front matter of The Original Sudoku had one, maybe two strategies that I had not thought of in all that time. It improved my game and my enjoyment of the game significantly. I'm sure the same information is on the web or in this thread, but I found that book explained it clearly and simply. I'm done now!
posted by AbelMelveny at 6:25 AM on July 4, 2023
posted by AbelMelveny at 6:25 AM on July 4, 2023
This thread is closed to new comments.
I also like Sudoku Daily for Mac, which has ~10 levels every day, plus a couple of tutorial levels, plus a full archive. It also explains how to solve the square if you ask for a hint. Some of them are so obscure that I still don't really understand them (e.g. flying fish with a wing), but this app has really helped me have a better handle on a solving strategy.
(I do a lot of sudoku)
posted by Sweetie Darling at 6:04 PM on July 3, 2023