## Stuck on 32x32 sudoku

Post the puzzle or solving technique that's causing you trouble and someone will help

### Stuck on 32x32 sudoku

Hi everyone,

Hopefully I can get help here with bigger sudokus than 9x9. I tried my luck with a 32x32 sudoku in a newspaper, but it stumped me.

I made a copy in Microsoft Excel to allow adding multiple pencilmarks, but this is as far as I got. (See the attachment.)

[Pencilmark explanation: - green cells contain values I filled in
- small texts are pencilmarks. For example, 2/A/D means the cell can only have those values
- lowercase pencilmarks: h means horizontally linked, v means vertically linked, b means box linked. For example, if a row can only contain three '2'-s, they are all marked as 2h. Combinations can exist, for example: 4vbh.]

I am not looking for the final solution (the solution is accessible at the end of the newspaper anyway), instead I want to know what the next step is and why. And in case I would get stuck again later, a step-by-step solution would be helpful for reference, but that may be too much to ask for.

Alternatively, if someone manages to solve it, I would glady hear about solving techniques that make solving giant sudokus easier.

NOTE: If necessary, I can manually re-type the puzzle with a different format to input it easier into solving tools. Just please clarify what the format should look like.
Attachments
32x32 Sudoku.xlsx
Partially solved sudoku with chaotic pencilmarks
Submachine

Posts: 4
Joined: 26 March 2021

### Re: Stuck on 32x32 sudoku

Code: Select all
` G Q . . E B . . . K . 7 . . . I O . 3 . 2 . . T . . . 0 9 4 . . F D . 1 . O . . . . 9 . E . 8 . . R . P S . . U G 7 3 Q . . K N P . U . . . . . 4 . . . . L 7 . 8 H . E . G . N J 9 . . R . . . 4 . O E . . F 8 I Q 2 U J S . . 9 B 5 . D . V C H 6 T . . . 1 7 3 R C . . 2 Q 6 G . . A H . . 0 M 4 U 7 . . 8 5 . . . . . . . D 7 . . T . K U H . S V C O . F . . . . . 3 6 J . L . E . Q . . 8 . . 8 . J . T . . E . F . M 1 V . . . C K O . . . . U 4 2 H . A H B V 9 . L . . M . 3 8 . 2 U Q S 1 F . 7 E . . . D I N . . . . . . Q U A F K . . 9 . R . . 5 . . E B V 1 3 . D M . G 2 H . 4 6 C . . . . 9 L Q 3 1 . . R . B M P G . 5 A T . . . . 6 . . . O F R G D H . 4 O . . L N . . . 2 . . 8 . . . J . E 0 V 7 . . 3 . . A J 9 . . . . M 2 . . . I . E S 4 U . . . C F . D . . . . . N 1 2 O 5 6 . I S P V C . 0 G 3 D 7 . . K R N 4 . . E 1 L . M B 8 J E T . F 2 D 1 . . G . P . . 9 . 3 . . N . 0 . . B . C . . . . R B V K . N E 0 . T . 8 . 1 4 H C L 6 . . . . . . Q I J . D . . . 1 . . 4 . J B G E . . I T F . O H . S . . . 6 K P 3 . . . . 0 C L P . . . . 2 K 5 8 . . . I . H E . 4 S U . . 3 V R F J G . . . Q . . O . . H . . . . . . . 3 G J 9 . 8 . D . 4 . A . K . 1 M . D . . . . . . E . . R . 2 . 4 . . . . . G . T . . U 9 L . . C . V 1 R C . G 4 I . . M E 5 P . . F . 6 U O . S 8 7 . H . J D . K U . . . . . D A . J Q . . . K F G 7 . L . . . 6 T . . . . S E 9 K 9 F . . U V N 6 . I 4 . . A . . . . . . M C . . G . . 8 R . 3 T 5 G . . 3 . . . . F L Q . S N D M . O . . K A I 0 4 . . . . H M E . J F 8 . S A . G K U 1 L . R 3 . . 9 . 7 . O Q D C 4 N . . . . . D K 0 7 . . . E M . 9 I 1 V S R . . B . F . . P . 6 8 5 L 0 . 3 V I 5 . . . . P 9 7 . . . 1 C N . 6 . E . . J . T . F . 4 6 . . M Q V C 4 . R T G . . O . U D E 3 P 7 H . N 8 1 . S . . 0 8 . 1 . . . . . Q O . . 4 . 6 D 7 . . G I . . 2 9 E M . . C H V S F E G 1 A 9 B 7 4 . V . H P U . . 8 I 5 N D M 3 C 0 6 T . R O . . . N . . 8 J L . S . . . Q 2 . . H . . . . 1 . . V 7 . U . E 9 K . . D S E U 8 . . 6 N . J . . 0 . 4 . V . . . L Q . 1 . 7 . . 7 L Q 3 H . . B . . 1 S C V E 6 . . . T 8 O . . . R D . . P G`

I've extracted the current state of the 32x32 sudoku, including solved cells, but excluding pencilmarks.
I'm assuming 0-9,A-V map to the numbers 1-32.

Grid in 1-32 format:
Code: Select all
` 17 27  .  . 15 12  .  .  . 21  .  8  .  .  . 19 25  .  4  .  3  .  . 30  .  .  .  1 10  5  .  . 16 14  .  2  . 25  .  .  .  . 10  . 15  .  9  .  . 28  . 26 29  .  . 31 17  8  4 27  .  . 21 24 26  . 31  .  .  .  .  .  5  .  .  .  . 22  8  .  9 18  . 15  . 17  . 24 20 10  .  . 28  .  .  .  5  . 25 15  .  . 16  9 19 27  3 31 20 29  .  . 10 12  6  . 14  . 32 13 18  7 30  .  .  .  2  8  4 28 13  .  .  3 27  7 17  .  . 11 18  .  .  1 23  5 31  8  .  .  9  6  .  .  .  .  .  .  . 14  8  .  . 30  . 21 31 18  . 29 32 13 25  . 16  .  .  .  .  .  4  7 20  . 22  . 15  . 27  .  .  9  .  .  9  . 20  . 30  .  . 15  . 16  . 23  2 32  .  .  . 13 21 25  .  .  .  . 31  5  3 18  . 11 18 12 32 10  . 22  .  . 23  .  4  9  .  3 31 27 29  2 16  .  8 15  .  .  . 14 19 24  .  .  .  .  .  . 27 31 11 16 21  .  . 10  . 28  .  .  6  .  . 15 12 32  2  4  . 14 23  . 17  3 18  .  5  7 13  .  .  .  . 10 22 27  4  2  .  . 28  . 12 23 26 17  .  6 11 30  .  .  .  .  7  .  .  . 25 16 28 17 14 18  .  5 25  .  . 22 24  .  .  .  3  .  .  9  .  .  . 20  . 15  1 32  8  .  .  4  .  . 11 20 10  .  .  .  . 23  3  .  .  . 19  . 15 29  5 31  .  .  . 13 16  . 14  .  .  .  .  . 24  2  3 25  6  7  . 19 29 26 32 13  .  1 17  4 14  8  .  . 21 28 24  5  .  . 15  2 22  . 23 12  9 20 15 30  . 16  3 14  2  .  . 17  . 26  .  . 10  .  4  .  . 24  .  1  .  . 12  . 13  .  .  .  . 28 12 32 21  . 24 15  1  . 30  .  9  .  2  5 18 13 22  7  .  .  .  .  .  . 27 19 20  . 14  .  .  .  2  .  .  5  . 20 12 17 15  .  . 19 30 16  . 25 18  . 29  .  .  .  7 21 26  4  .  .  .  .  1 13 22 26  .  .  .  .  3 21  6  9  .  .  . 19  . 18 15  .  5 29 31  .  .  4 32 28 16 20 17  .  .  . 27  .  . 25  .  . 18  .  .  .  .  .  .  .  4 17 20 10  .  9  . 14  .  5  . 11  . 21  .  2 23  . 14  .  .  .  .  .  . 15  .  . 28  .  3  .  5  .  .  .  .  . 17  . 30  .  . 31 10 22  .  . 13  . 32  2 28 13  . 17  5 19  .  . 23 15  6 26  .  . 16  .  7 31 25  . 29  9  8  . 18  . 20 14  . 21 31  .  .  .  .  . 14 11  . 20 27  .  .  . 21 16 17  8  . 22  .  .  .  7 30  .  .  .  . 29 15 10 21 10 16  .  . 31 32 24  7  . 19  5  .  . 11  .  .  .  .  .  . 23 13  .  . 17  .  .  9 28  .  4 30  6 17  .  .  4  .  .  .  . 16 22 27  . 29 24 14 23  . 25  .  . 21 11 19  1  5  .  .  .  . 18 23 15  . 20 16  9  . 29 11  . 17 21 31  2 22  . 28  4  .  . 10  .  8  . 25 27 14 13  5 24  .  .  .  .  . 14 21  1  8  .  .  . 15 23  . 10 19  2 32 29 28  .  . 12  . 16  .  . 26  .  7  9  6 22  1  .  4 32 19  6  .  .  .  . 26 10  8  .  .  .  2 13 24  .  7  . 15  .  . 20  . 30  . 16  .  5  7  .  . 23 27 32 13  5  . 28 30 17  .  . 25  . 31 14 15  4 26  8 18  . 24  9  2  . 29  .  .  1  9  .  2  .  .  .  .  . 27 25  .  .  5  .  7 14  8  .  . 17 19  .  .  3 10 15 23  .  . 13 18 32 29 16 15 17  2 11 10 12  8  5  . 32  . 18 26 31  .  .  9 19  6 24 14 23  4 13  1  7 30  . 28 25  .  .  . 24  .  .  9 20 22  . 29  .  .  . 27  3  .  . 18  .  .  .  .  2  .  . 32  8  . 31  . 15 10 21  .  . 14 29 15 31  9  .  .  7 24  . 20  .  .  1  .  5  . 32  .  .  . 22 27  .  2  .  8  .  .  8 22 27  4 18  .  . 12  .  .  2 29 13 32 15  7  .  .  . 30  9 25  .  .  . 28 14  .  . 26 17`

Now I just need a 32x32 sudoku solver!

 Fixed missing dots (empty cells) at end of a couple of lines. Thx to creint for pointing this out.
Last edited by 1to9only on Fri Mar 26, 2021 11:23 pm, edited 1 time in total.
1to9only

Posts: 4069
Joined: 04 April 2018

### Re: Stuck on 32x32 sudoku

Next Steps:: Show
Naked Single: R16C15: 24
Naked Single: R5C15: 30
Naked Single: R20C15: 1
I'm using 1-32 number format, so you'll have to convert 1-32 to 0-9,A-V.

Afterwards:: Show
There is a quite a bunch of Pointing and Claiming that follows after above.
1to9only

Posts: 4069
Joined: 04 April 2018

### Re: Stuck on 32x32 sudoku

1to9only: you were missing one last . in your format, 31 items on one line.
Code: Select all
` 12 32 21  . 24 15  1  . 30  .  9  .  2  5 18 13 22  7  .  .  .  .  .  . 27 19 20  . 14  .  .`

Code: Select all
` 27  .  . 25  .  . 18  .  .  .  .  .  .  .  4 17 20 10  .  9  . 14  .  5  . 11  . 21  .  2 23`

It needs some rounds of locked singles, if you don't use the naked singles you may need many rounds of sets.
Easiest advise is just to solve it with a solver, it saves a lot of time.

It is not about needing more techniques to solve those, because most of them just use the basics. It's more about looking in the right places to save time. Looking randomly is very ineffective.

Scan the whole grid once for singles + locked singles. Not applying your result. Yes this takes a lot of time and it feels like you don't make progress. Finding naked singles without pencilmarks is hard, but if you don't create pencilmarks than you still need them in this puzzle for sets if you don't use them.

If find a single you write down your excluded pencilmark locations.
Make sure you never miss anything or else you need to start scanning the whole puzzle again for something if your affected constraints dry up.

Apply your results and repeat but this time look only in your affected constraints.
You only need to scan affected cells for naked singles.
And scan affected digits in constraints for hidden single/locked singles.
Example: -1r1c1 -> scan r1c1, 1r1, 1c1, 1b1; you don't need to scan other digits in row 1.
r1c1 only 1 pencilmark left in cell?
1r1 only 1 pencilmark left or is the group pencilmarks of digit 1 contained in another constraint?

You can skip delays scanning for locked singles but you should resume scanning where you left off, maybe in reverse gives faster results.
On larger puzzles the chance of finding something at random decreases.

Example layout
Step 1
-1r1c1
-2r1c2
Scanlist 1
[constraint, hidden single, naked single, locked single]
r1c1, x, x, x
r1c2, x, x
1r1
1c1
1b1
2r1
2c1
2b1

You could keep seperate tables to index pencilmarks, but more bookkeeping can give errors.
For this puzzle you need ~160+ steps. 2500 initial pencilmarks / 160 = ~15 pencilmarks each step, 450 initial empty cells / 160 = ~3 filled cell each step.
I could generate one that only takes ~6 steps where the chance of finding something is much higher.

Let me know if this method works for manual solving.
creint

Posts: 339
Joined: 20 January 2018

### Re: Stuck on 32x32 sudoku

Thanks for the responses! I must have been really tired to not notice that single. Especially ironic if you see my pencilmark for that cell.

I already scanned the entire grid for naked singles, that was the only one I missed.

I would like to use a solver, but most online tools I found were for 9x9 grids. And I do use pencilmarks, though I may be thinking of something different. Most of the time when I finish all basic techniques I know of and don't find anything, I am left with looking randomly, which - as you said - is indeed very ineffective.

Today I started creating an even bigger grid, where each cell is a 6x6 grid containing all possible values. In this bigger grid, I can keep track of ruled out values easier, but it will be a lot of time to make. (And it will all be manual, so errors can happen, as already proved by the missed single.)
Submachine

Posts: 4
Joined: 26 March 2021

### Re: Stuck on 32x32 sudoku

Submachine wrote:Today I started creating an even bigger grid, where each cell is a 6x6 grid containing all possible values. In this bigger grid, I can keep track of ruled out values easier, but it will be a lot of time to make. (And it will all be manual, so errors can happen, as already proved by the missed single.)

You want to create manually a large grid instead of solving one?
My solver can do all those things. If you cannot paste it then you need to do manual designing, cells+constraint. Probably complex for other users.
creint

Posts: 339
Joined: 20 January 2018

### Re: Stuck on 32x32 sudoku

See: http://forum.enjoysudoku.com/giant-sudoku-s-16x16-25x25-36x36-100x100-t6578.html
Near the end of the thread, the 25x25 and 36x36 sudokus posted are solvable with singles only.
The last post has a link to a github repo that contains some pascal source code.
1to9only

Posts: 4069
Joined: 04 April 2018

### Re: Stuck on 32x32 sudoku

1to9only wrote:See: http://forum.enjoysudoku.com/giant-sudoku-s-16x16-25x25-36x36-100x100-t6578.html
Near the end of the thread, the 25x25 and 36x36 sudokus posted are solvable with singles only.
The last post has a link to a github repo that contains some pascal source code.

Thank you, though I am still trying to solve my current puzzle first. And the size of this puzzle is 32x32, which does not fit the description.

creint wrote:You want to create manually a large grid instead of solving one? My solver can do all those things.

No no, I still intend to solve it. But you said I need more pencilmarks to solve this puzzle, and creating a larger grid is my only way to keep track of 2-to-32 pencilmarks per cell.

There may be a confusion, because I did not receive a solver (you said your solver can do it, but I don't have it). But I would be happy to receive one. I just don't know much about github and pascal source codes, so I would prefer something with a user-friendly interface.

Should I create a new post in a different subtopic to look for a solver?
Submachine

Posts: 4
Joined: 26 March 2021

### Re: Stuck on 32x32 sudoku

For the partially solved 32x32 sudoku in post #1:
Solution Path:: Show
Code: Select all
`Naked Single: R16C15: 24Naked Single: R5C15: 30Naked Single: R20C15: 1Pointing: Cells R1C3,R2C3: 20 in block and column: -20r25c3, -20r27c3Pointing: Cells R4C20,R8C20: 21 in block and column: -21r32c20, -21r26c20, -21r19c20, -21r30c20Pointing: Cells R1C22,R2C22: 18 in block and column: -18r19c22, -18r24c22, -18r21c22Pointing: Cells R2C23,R8C23: 5 in block and column: -5r30c23, -5r25c23Pointing: Cells R12C4,R15C4: 4 in block and column: -4r19c4, -4r21c4Pointing: Cells R12C4,R15C4: 26 in block and column: -26r28c4, -26r31c4Pointing: Cells R9C26,R10C26: 24 in block and column: -24r20c26, -24r21c26Pointing: Cells R11C28,R13C28,R15C28: 16 in block and column: -16r3c28, -16r5c28, -16r28c28, -16r31c28, -16r27c28Pointing: Cells R12C28,R15C28,R16C28: 28 in block and column: -28r4c28, -28r6c28Pointing: Cells R17C5,R19C5,R21C5,R22C5: 25 in block and column: -25r30c5Pointing: Cells R18C14,R21C14,R23C14: 28 in block and column: -28r26c14, -28r31c14, -28r6c14, -28r30c14, -28r1c14, -28r28c14Pointing: Cells R18C19,R21C19,R23C19: 13 in block and column: -13r11c19Pointing: Cells R18C29,R19C29: 16 in block and column: -16r5c29Pointing: Cells R25C10,R26C10,R31C10,R32C10: 3 in block and column: -3r18c10, -3r20c10, -3r24c10, -3r22c10, -3r23c10Pointing: Cells R21C26,R21C28: 23 in block and row: -23r21c13, -23r21c6, -23r21c5Pointing: Cells R17C13,R17C15: 23 in block and row: -23r17c6, -23r17c5Claiming: Cells R8C29,R8C30: 25 in row and block: -25r5c30, -25r5c29, -25r3c30Claiming: Cells R25C9,R25C10: 24 in row and block: -24r32c10, -24r28c12Claiming: Cells R17C12,R18C12,R19C12,R21C12: 24 in column and block: -24r18c10, -24r20c10, -24r20c9, -24r19c9, -24r19c10, -24r21c9, -24r18c9Hidden Single: R20C18: 24 in rowHidden Single: R20C31: 11 in rowHidden Single: R20C22: 27 in rowHidden Single: R20C26: 3 in rowHidden Single: R3C27: 3 in blockHidden Single: R20C5: 22 in rowNaked Single: R17C22: 2Naked Single: R20C9: 10Hidden Single: R17C13: 10 in blockHidden Single: R6C16: 10 in blockHidden Single: R2C16: 5 in blockHidden Single: R8C23: 5 in blockHidden Single: R6C5: 5 in blockHidden Single: R17C15: 23 in blockHidden Single: R30C13: 23 in blockHidden Single: R27C13: 16 in blockHidden Single: R11C9: 16 in columnHidden Single: R9C13: 1 in columnHidden Single: R1C15: 13 in columnHidden Single: R8C25: 13 in blockHidden Single: R2C29: 13 in blockPointing: Cells R19C9,R21C9,R23C9: 2 in block and column: -2r6c9, -2r1c9Hidden Single: R6C28: 2 in rowHidden Single: R5C11: 2 in rowPointing: Cells R26C7,R32C7: 23 in block and column: -23r1c7, -23r2c7, -23r19c7, -23r3c7Pointing: Cells R3C11,R3C12: 25 in block and row: -25r3c28Pointing: Cells R4C15,R4C16: 28 in block and row: -28r4c22, -28r4c6, -28r4c5Pointing: Cells R5C25,R5C26,R5C27: 21 in block and row: -21r5c14, -21r5c4Hidden Single: R3C4: 21 in blockPointing: Cells R22C13,R22C14: 14 in block and row: -14r22c10Claiming: Cells R5C30,R5C31: 20 in row and block: -20r1c31, -20r8c31, -20r2c30, -20r8c30Hidden Single: R8C20: 20 in rowHidden Single: R1C20: 7 in blockHidden Single: R4C20: 21 in blockHidden Single: R8C13: 21 in blockHidden Single: R8C7: 11 in rowHidden Single: R26C7: 17 in columnHidden Single: R32C7: 23 in blockHidden Single: R4C15: 17 in columnHidden Single: R26C15: 28 in columnHidden Single: R8C5: 17 in blockHidden Single: R4C16: 28 in blockHidden Single: R4C29: 4 in rowHidden Single: R30C31: 4 in blockHidden Single: R26C31: 14 in blockHidden Single: R29C30: 27 in blockHidden Single: R26C20: 23 in rowHidden Single: R25C20: 27 in blockHidden Single: R26C24: 27 in blockHidden Single: R32C29: 24 in rowNaked Single: R29C13: 22Hidden Single: R27C24: 22 in rowHidden Single: R26C8: 22 in rowHidden Single: R25C8: 25 in blockHidden Single: R30C1: 25 in blockHidden Single: R32C8: 3 in blockHidden Single: R28C8: 16 in blockHidden Single: R31C19: 25 in blockHidden Single: R14C18: 25 in blockHidden Single: R26C27: 25 in blockHidden Single: R25C3: 30 in rowHidden Single: R31C3: 26 in rowNaked Single: R25C1: 20Hidden Single: R32C24: 20 in blockPointing: Cells R1C13,R7C13: 26 in block and column: -26r11c13Pointing: Cells R10C19,R14C19: 20 in block and column: -20r28c19Pointing: Cells R25C2,R26C2: 18 in block and column: -18r19c2, -18r21c2Pointing: Cells R26C22,R28C22: 29 in block and column: -29r15c22Pointing: Cells R30C22,R30C23: 10 in block and row: -10r30c20Pointing: Cells R32C19,R32C20: 10 in block and row: -10r32c30Pointing: Cells R27C30,R27C31: 20 in block and row: -20r27c9Naked Single: R27C9: 21Naked Single: R29C11: 20Hidden Single: R28C18: 20 in blockHidden Single: R28C19: 22 in blockHidden Single: R30C18: 26 in blockClaiming: Cells R1C9,R6C9,R7C9: 14 in column and block: -14r3c12, -14r7c11, -14r3c10, -14r3c11, -14r1c11Claiming: Cells R29C17,R29C18: 3 in row and block: -3r31c17Claiming: Cells R29C17,R29C18: 21 in row and block: -21r32c18, -21r30c17Claiming: Cells R32C10,R32C11: 1 in row and block: -1r28c11, -1r30c10Claiming: Cells R32C25,R32C26: 5 in row and block: -5r30c25, -5r25c25, -5r30c26, -5r25c26Naked Single: R25C26: 18Hidden Single: R26C2: 18 in blockNaked Single: R26C9: 31Hidden Single: R32C25: 31 in rowHidden Single: R32C26: 5 in blockHidden Single: R10C25: 5 in blockHidden Single: R14C11: 5 in blockHidden Single: R32C30: 21 in rowPointing: Cells R12C10,R12C11: 7 in block and row: -7r12c6, -7r12c7, -7r12c5, -7r12c14Hidden Single: R11C5: 7 in blockHidden Single: R30C6: 7 in blockNaked Single: R11C13: 11Naked Single: R25C13: 4Hidden Single: R3C16: 4 in blockHidden Single: R7C8: 4 in blockHidden Single: R7C6: 8 in blockHidden Single: R5C5: 10 in blockHidden Single: R3C5: 29 in blockHidden Single: R12C7: 4 in blockHidden Single: R15C4: 4 in blockHidden Single: R12C4: 26 in blockHidden Single: R23C8: 10 in blockPointing: Cells R1C14,R2C14,R6C14: 6 in block and column: -6r31c14, -6r30c14, -6r27c14, -6r28c14Pointing: Cells R1C14,R2C14,R6C14: 11 in block and column: -11r26c14, -11r31c14, -11r30c14, -11r27c14, -11r28c14Naked Single: R27C14: 12Hidden Single: R26C29: 12 in rowNaked Single: R5C14: 24Hidden Single: R25C10: 24 in columnNaked Single: R25C9: 13Hidden Single: R30C2: 13 in blockHidden Single: R31C21: 13 in blockNaked Single: R25C21: 5Hidden Single: R30C3: 5 in blockHidden Single: R21C2: 5 in blockHidden Single: R19C2: 4 in blockNaked Single: R28C29: 11Naked Single: R28C2: 31Hidden Single: R25C23: 31 in blockHidden Single: R25C28: 17 in rowNaked Single: R28C11: 6Naked Single: R28C12: 4Hidden Single: R20C10: 4 in blockHidden Single: R21C28: 4 in blockHidden Single: R21C26: 23 in blockHidden Single: R31C23: 4 in blockHidden Single: R20C16: 30 in rowHidden Single: R20C28: 12 in rowHidden Single: R30C26: 12 in blockHidden Single: R5C27: 12 in blockHidden Single: R31C17: 12 in blockHidden Single: R28C4: 12 in blockHidden Single: R31C4: 28 in blockHidden Single: R32C1: 6 in blockHidden Single: R30C17: 6 in blockHidden Single: R30C20: 30 in blockHidden Single: R12C27: 21 in columnHidden Single: R10C11: 21 in blockHidden Single: R5C26: 21 in columnHidden Single: R5C28: 25 in blockHidden Single: R3C28: 32 in blockHidden Single: R4C28: 23 in blockHidden Single: R1C26: 16 in columnHidden Single: R31C14: 30 in rowHidden Single: R30C14: 17 in blockHidden Single: R28C14: 1 in blockHidden Single: R31C24: 17 in blockHidden Single: R15C23: 17 in blockHidden Single: R12C30: 17 in blockHidden Single: R28C22: 21 in rowHidden Single: R26C22: 29 in blockHidden Single: R28C28: 29 in blockHidden Single: R30C25: 21 in rowHidden Single: R31C25: 16 in blockHidden Single: R30C10: 16 in rowHidden Single: R30C12: 14 in blockHidden Single: R17C11: 14 in blockHidden Single: R16C10: 14 in blockHidden Single: R15C10: 23 in blockHidden Single: R10C19: 14 in blockHidden Single: R6C20: 14 in blockHidden Single: R14C19: 20 in blockHidden Single: R11C19: 23 in blockHidden Single: R11C20: 2 in blockHidden Single: R18C11: 13 in blockHidden Single: R21C13: 13 in blockHidden Single: R23C19: 13 in blockHidden Single: R17C5: 13 in columnHidden Single: R3C6: 13 in columnHidden Single: R2C5: 23 in blockHidden Single: R19C6: 23 in blockHidden Single: R21C6: 2 in blockHidden Single: R17C6: 27 in blockHidden Single: R14C13: 9 in columnHidden Single: R18C13: 32 in columnHidden Single: R9C2: 9 in rowHidden Single: R16C2: 22 in blockHidden Single: R23C9: 2 in rowHidden Single: R30C29: 19 in rowHidden Single: R32C10: 19 in rowHidden Single: R32C11: 1 in blockHidden Single: R31C28: 19 in rowHidden Single: R27C28: 6 in blockHidden Single: R31C16: 6 in blockNaked Single: R5C10: 26Naked Single: R5C25: 29Naked Single: R9C14: 20Hidden Single: R10C12: 20 in blockNaked Single: R12C20: 1Naked Single: R15C21: 28Naked Single: R27C16: 11Hidden Single: R25C2: 11 in blockHidden Single: R25C25: 3 in rowHidden Single: R26C25: 11 in blockHidden Single: R1C27: 11 in blockHidden Single: R1C25: 9 in blockHidden Single: R7C25: 28 in blockHidden Single: R31C10: 11 in columnHidden Single: R26C10: 3 in blockHidden Single: R31C11: 18 in blockHidden Single: R4C22: 11 in rowHidden Single: R30C23: 11 in blockHidden Single: R30C21: 1 in blockHidden Single: R30C22: 10 in blockHidden Single: R28C23: 28 in blockHidden Single: R30C5: 28 in rowHidden Single: R12C6: 28 in blockHidden Single: R16C28: 28 in blockHidden Single: R3C19: 11 in rowHidden Single: R4C30: 22 in rowNaked Single: R1C11: 22Hidden Single: R7C18: 22 in blockHidden Single: R5C4: 22 in blockHidden Single: R2C22: 22 in columnHidden Single: R1C22: 18 in blockNaked Single: R1C18: 32Hidden Single: R2C8: 32 in blockNaked Single: R5C21: 16Hidden Single: R3C31: 16 in blockHidden Single: R19C22: 16 in blockHidden Single: R18C29: 16 in blockHidden Single: R22C31: 22 in blockHidden Single: R19C32: 27 in blockNaked Single: R5C22: 19Naked Single: R32C19: 10Pointing: Cells R2C3,R6C3: 11 in block and column: -11r17c3, -11r19c3Pointing: Cells R3C13,R7C13: 12 in block and column: -12r22c13Naked Single: R22C13: 14Hidden Single: R1C14: 14 in blockHidden Single: R3C8: 14 in blockHidden Single: R1C8: 2 in blockHidden Single: R7C9: 14 in blockHidden Single: R3C23: 2 in blockHidden Single: R3C21: 27 in rowHidden Single: R1C23: 23 in blockHidden Single: R16C18: 27 in rowHidden Single: R13C23: 27 in rowNaked Single: R1C13: 26Naked Single: R11C21: 12Pointing: Cells R6C26,R7C26: 6 in block and column: -6r12c26, -6r14c26Hidden Single: R16C27: 6 in blockHidden Single: R21C27: 9 in columnHidden Single: R18C27: 24 in blockHidden Single: R22C27: 29 in columnNaked Single: R14C26: 29Hidden Single: R9C9: 29 in rowNaked Single: R10C26: 24Hidden Single: R9C1: 24 in blockHidden Single: R7C1: 19 in columnNaked Single: R14C9: 18Pointing: Cells R14C3,R16C3: 23 in block and column: -23r6c3Pointing: Cells R9C17,R11C17: 19 in block and column: -19r6c17, -19r19c17, -19r2c17Pointing: Cells R17C3,R19C3,R21C3: 24 in block and column: -24r6c3, -24r1c3Pointing: Cells R18C10,R19C10,R22C10,R23C10: 8 in block and column: -8r12c10Pointing: Cells R2C17,R2C19: 30 in block and row: -30r2c10, -30r2c30, -30r2c12Pointing: Cells R10C2,R10C3,R10C4: 29 in block and row: -29r10c24Hidden Single: R15C24: 29 in blockHidden Single: R12C24: 25 in blockHidden Single: R9C26: 25 in blockHidden Single: R15C12: 25 in blockHidden Single: R3C11: 25 in blockHidden Single: R12C26: 30 in blockHidden Single: R17C30: 25 in rowHidden Single: R8C29: 25 in blockNaked Single: R9C11: 8Naked Single: R12C19: 8Naked Single: R15C19: 3Pointing: Cells R2C30,R3C30,R6C30,R8C30: 1 in block and column: -1r19c30Pointing: Cells R10C30,R16C30: 3 in block and column: -3r31c30, -3r27c30, -3r23c30Hidden Single: R31C32: 3 in rowHidden Single: R31C30: 23 in rowHidden Single: R3C32: 23 in blockHidden Single: R6C2: 23 in blockPointing: Cells R2C3,R6C3: 3 in block and column: -3r24c3, -3r27c3, -3r18c3, -3r21c3Hidden Single: R27C2: 3 in blockHidden Single: R27C3: 19 in blockPointing: Cells R6C31,R7C31: 12 in block and column: -12r17c31, -12r24c31, -12r23c31Pointing: Cells R10C2,R10C4: 19 in block and row: -19r10c30, -19r10c23, -19r10c24Naked Single: R10C23: 3Hidden Single: R16C30: 3 in blockHidden Single: R16C20: 10 in rowHidden Single: R16C11: 11 in rowHidden Single: R13C11: 31 in blockHidden Single: R18C12: 3 in rowHidden Single: R19C12: 29 in blockHidden Single: R19C3: 24 in rowNaked Single: R16C22: 31Hidden Single: R10C5: 31 in blockHidden Single: R10C28: 9 in rowHidden Single: R10C24: 18 in rowHidden Single: R14C24: 8 in blockNaked Single: R10C14: 32Naked Single: R12C14: 27Hidden Single: R11C12: 27 in blockHidden Single: R14C31: 27 in blockNaked Single: R12C28: 18Hidden Single: R13C5: 18 in blockNaked Single: R13C24: 10Hidden Single: R7C23: 10 in blockNaked Single: R14C3: 23Hidden Single: R16C21: 23 in blockHidden Single: R12C21: 9 in blockHidden Single: R16C5: 9 in blockHidden Single: R15C8: 8 in blockHidden Single: R12C5: 32 in blockHidden Single: R14C21: 32 in blockHidden Single: R16C29: 32 in blockHidden Single: R16C3: 8 in rowHidden Single: R18C21: 22 in columnHidden Single: R12C29: 22 in rowHidden Single: R17C4: 8 in rowHidden Single: R19C4: 11 in blockHidden Single: R23C4: 9 in blockHidden Single: R17C18: 11 in blockHidden Single: R32C20: 11 in blockHidden Single: R32C18: 16 in rowHidden Single: R13C17: 11 in blockHidden Single: R15C20: 16 in blockHidden Single: R13C28: 16 in blockHidden Single: R13C18: 30 in rowHidden Single: R18C14: 15 in rowHidden Single: R18C8: 28 in rowHidden Single: R1C7: 28 in blockHidden Single: R4C6: 24 in blockHidden Single: R7C2: 24 in blockHidden Single: R4C5: 26 in blockHidden Single: R4C2: 1 in rowHidden Single: R8C8: 1 in blockHidden Single: R6C9: 28 in blockHidden Single: R1C9: 24 in blockHidden Single: R2C9: 20 in blockHidden Single: R1C3: 20 in blockHidden Single: R6C17: 24 in blockHidden Single: R8C24: 28 in blockHidden Single: R28C7: 24 in blockHidden Single: R28C6: 26 in blockHidden Single: R28C5: 30 in blockHidden Single: R18C6: 30 in columnHidden Single: R21C19: 32 in rowNaked Single: R3C2: 7Hidden Single: R7C13: 7 in columnHidden Single: R3C13: 12 in columnHidden Single: R12C11: 7 in columnHidden Single: R7C11: 12 in columnHidden Single: R6C31: 12 in blockHidden Single: R2C23: 12 in blockHidden Single: R7C31: 17 in blockHidden Single: R6C19: 17 in blockHidden Single: R7C4: 29 in rowHidden Single: R1C4: 6 in blockHidden Single: R7C26: 6 in rowHidden Single: R6C26: 26 in blockHidden Single: R7C24: 26 in blockHidden Single: R6C24: 1 in blockNaked Single: R5C29: 15Hidden Single: R10C30: 15 in blockHidden Single: R10C29: 8 in blockNaked Single: R14C8: 6Naked Single: R21C21: 18Hidden Single: R24C3: 18 in blockHidden Single: R2C12: 18 in columnNaked Single: R22C24: 12Naked Single: R22C16: 20Hidden Single: R23C21: 20 in blockHidden Single: R22C21: 15 in columnHidden Single: R19C7: 20 in blockHidden Single: R23C28: 15 in blockHidden Single: R22C28: 26 in blockPointing: Cells R2C7,R3C7: 6 in block and column: -6r24c7Pointing: Cells R2C10,R3C10: 1 in block and column: -1r18c10, -1r24c10, -1r19c10, -1r22c10Hidden Single: R24C19: 1 in rowHidden Single: R7C17: 1 in rowHidden Single: R7C19: 27 in rowHidden Single: R22C17: 27 in blockHidden Single: R22C19: 30 in blockHidden Single: R2C17: 30 in blockHidden Single: R6C18: 3 in blockHidden Single: R2C19: 19 in blockHidden Single: R2C3: 3 in blockHidden Single: R6C3: 11 in blockHidden Single: R3C7: 19 in blockHidden Single: R2C7: 6 in blockHidden Single: R6C14: 6 in blockHidden Single: R2C14: 11 in blockHidden Single: R6C30: 19 in rowHidden Single: R19C19: 2 in blockHidden Single: R18C19: 26 in columnHidden Single: R19C18: 19 in blockHidden Single: R22C18: 6 in blockHidden Single: R29C18: 21 in columnHidden Single: R29C17: 3 in blockHidden Single: R19C17: 21 in blockHidden Single: R22C25: 2 in blockHidden Single: R24C24: 19 in columnHidden Single: R19C24: 32 in columnHidden Single: R18C32: 19 in blockHidden Single: R11C31: 19 in blockHidden Single: R9C17: 19 in blockHidden Single: R11C17: 13 in blockHidden Single: R9C8: 13 in blockHidden Single: R11C8: 30 in blockHidden Single: R14C23: 19 in blockHidden Single: R9C23: 22 in blockHidden Single: R14C16: 22 in blockHidden Single: R14C14: 7 in blockHidden Single: R11C14: 31 in blockHidden Single: R11C16: 21 in blockHidden Single: R9C16: 26 in blockHidden Single: R9C30: 30 in rowHidden Single: R14C29: 21 in blockHidden Single: R11C32: 29 in blockHidden Single: R1C31: 29 in blockHidden Single: R1C32: 31 in rowHidden Single: R15C31: 31 in blockHidden Single: R14C28: 31 in blockHidden Single: R14C30: 11 in rowHidden Single: R15C28: 11 in blockHidden Single: R11C28: 10 in blockHidden Single: R15C30: 10 in blockHidden Single: R21C4: 19 in blockHidden Single: R10C2: 19 in blockHidden Single: R18C2: 29 in columnHidden Single: R10C3: 29 in blockHidden Single: R10C4: 1 in blockHidden Single: R22C4: 3 in columnHidden Single: R24C20: 3 in blockHidden Single: R19C20: 12 in blockHidden Single: R22C20: 18 in blockHidden Single: R19C10: 18 in blockHidden Single: R24C16: 12 in blockHidden Single: R19C16: 7 in blockHidden Single: R26C16: 9 in columnHidden Single: R26C14: 21 in blockHidden Single: R19C14: 9 in blockHidden Single: R18C25: 7 in blockHidden Single: R19C25: 6 in blockHidden Single: R17C3: 7 in blockHidden Single: R23C31: 3 in blockHidden Single: R21C22: 3 in blockHidden Single: R23C22: 28 in blockHidden Single: R21C14: 28 in blockHidden Single: R22C14: 25 in blockHidden Single: R23C14: 8 in blockHidden Single: R19C30: 8 in blockHidden Single: R17C32: 12 in blockHidden Single: R23C29: 31 in blockHidden Single: R18C10: 31 in blockHidden Single: R22C10: 8 in blockHidden Single: R22C5: 1 in rowHidden Single: R18C5: 8 in blockHidden Single: R21C5: 6 in blockHidden Single: R23C5: 12 in blockHidden Single: R19C5: 25 in columnHidden Single: R21C12: 12 in blockHidden Single: R12C10: 12 in blockHidden Single: R12C12: 6 in blockHidden Single: R18C3: 12 in blockHidden Single: R21C3: 1 in blockHidden Single: R17C12: 24 in blockHidden Single: R3C12: 30 in columnHidden Single: R21C9: 25 in blockHidden Single: R19C9: 26 in blockHidden Single: R18C9: 1 in columnHidden Single: R18C23: 6 in rowHidden Single: R19C29: 1 in rowHidden Single: R15C22: 6 in blockHidden Single: R11C23: 26 in blockHidden Single: R24C22: 26 in columnHidden Single: R11C29: 6 in rowHidden Single: R15C32: 26 in blockHidden Single: R21C29: 26 in columnHidden Single: R21C23: 24 in rowHidden Single: R17C23: 1 in blockHidden Single: R17C31: 30 in rowHidden Single: R8C30: 26 in blockHidden Single: R8C32: 30 in blockHidden Single: R24C32: 6 in columnHidden Single: R3C30: 6 in blockHidden Single: R3C10: 1 in rowHidden Single: R8C10: 6 in blockHidden Single: R2C10: 7 in blockHidden Single: R2C30: 1 in rowHidden Single: R8C31: 7 in rowHidden Single: R23C7: 26 in blockHidden Single: R24C7: 7 in blockHidden Single: R24C10: 30 in blockHidden Single: R23C10: 32 in blockHidden Single: R23C30: 7 in rowHidden Single: R24C31: 32 in blockHidden Single: R5C30: 32 in blockHidden Single: R5C31: 20 in blockHidden Single: R27C30: 20 in columnHidden Single: R27C31: 10 in block`
1to9only

Posts: 4069
Joined: 04 April 2018

### Re: Stuck on 32x32 sudoku

I managed to make a breakthrough earlier with this hint from creint:

if you don't create pencilmarks than you still need them in this puzzle for sets

I created another grid for pencilmarks only, and it made solving easier. I managed to fill in 47 cells just with the help of an extra grid for pencilmarks, and I will not miss a naked single again.

Now I came back because I ran out of ideas again, but wow, thank you 1to9only for creating the play-by-play. I already found the next move with it, and extended my solving method to not miss this type of clue again.

What I missed: Show
My mistake was as follows: I assumed I only need to check for hidden singles once for every letter, because I wrote down, after every new input, whether there are rows/columns/blocks that can only have the value in 3 or less positions. And after I occupied a cell that had such a note, I knew when a new hidden single was created. However, the letter A could be in 4 possible places in a row when I checked it, so I did not mark it with notes. And after I unknowingly filled in 3 of the cells in that row, I could not know that a new hidden single was created. So my solution to this problem is: Every time I am stuck, check all letters again for hidden singles.
Submachine

Posts: 4
Joined: 26 March 2021