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Questions tagged [sudoku]

A Sudoku is a puzzle consisting of a grid to be filled with symbols, such that each constraining unit contains each symbol exactly once. The typical example is a 9x9 square to be filled with the numbers 1 to 9, where the constraining units are rows, columns, and 3x3 blocks.

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16 votes
1 answer
2k views

What's the one digit you can fill in this partially hidden Sudoku?

A few weeks ago, I challenged some people to solve the puzzle I made. Two of them took it more or less seriously, but couldn't find the right solution. Now they are excited to see whether or not ...
Paul Kolk's user avatar
  • 270
16 votes
2 answers
849 views

When in Rome... – a deconstruction sudoku

This is part 63 of the puzzle series Around the World in Many Days. Each part is solvable on its own. Dear Puzzling, This is a sudoku deconstruction puzzle. Draw eight non-overlapping rectangular ...
Jafe's user avatar
  • 78k
2 votes
0 answers
76 views

What is the number of essentially different solutions for a 3Doku?

The 3Doku is a Sudoku-like puzzle with blocks of 4×4 cells on the faces of a cube. Instead of columns and rows, it has bands of cells that loop around the cube. It has me wondering how many ...
SQB's user avatar
  • 5,148
2 votes
1 answer
166 views

Minimally clued 2x3 Sudoku

Beginner puzzleThis puzzle is intended to be suitable for people who are new to puzzle solving. However, both experienced solvers and new solvers are welcome to post solutions to this puzzle. ...
CrSb0001's user avatar
  • 2,413
5 votes
1 answer
265 views

A final Colombian Sudoku... for the time being

This too is a Colombian Sudoku by Xavier Castillo. The usual rules apply. The dots outside the board on top indicate how many cells in the corresponding column or row of that board contain precisely ...
Bernardo Recamán Santos's user avatar
7 votes
2 answers
818 views

A Difficult Colombian Sudoku?

This Colombian Sudoku is by Xavier Castillo. Usual Sudoku rules apply. Additionally, digits on each of the two diagonals must all be different. The dots outside the board above indicate how many cells ...
Bernardo Recamán Santos's user avatar
12 votes
2 answers
460 views

A Crabby Sudoku

I present a *deep breath* Even-Odd TetroThermoDoku. From the back of the name to the front: Rules Sudoku: Fill each cell with a digit 1-9 such that no number repeats in any row, column, or 3x3 heavy-...
bobble's user avatar
  • 10.4k
7 votes
2 answers
361 views

Product = Sum Sudoku (Royal Statistical Society Christmas Quiz 2023)

Normal Sudoku rules for this grid size apply. The product of the numbers on each pink diagonal equals the sum of the numbers in the blue square. This puzzle is from the now closed contest at: https:/...
Will.Octagon.Gibson's user avatar
0 votes
0 answers
201 views

Continue with sudoku - how do I scan for next steps?

I filled some cells, but am stuck here. I cannot go any further. How do I advance? How would I scan the Sudoku to recognize next steps? I've taken the puzzle from https://play.google.com/store/apps/...
Abbas Baghirov's user avatar
5 votes
1 answer
495 views

Is the 7-clue 6x6 Sudoku solvable?

So I was trying to find an 8-clue 6x6 Sudoku because I knew from this paper that only 8 clues were needed to create a 6x6 Sudoku with a unique solution. However, I have managed to find one with 7 ...
CrSb0001's user avatar
  • 2,413
7 votes
1 answer
317 views

An Irregular Colombian Sudoku

Solve the Irregular Sudoku below (by Xavier Castillo), where the usual rules apply. The dots outside the board on top indicate how many cells in the corresponding column or row of that board contain ...
Bernardo Recamán Santos's user avatar
19 votes
1 answer
1k views

Mercury in Centigrade

This is part 55 of the puzzle series Around the World in Many Days. Each part is solvable on its own. Dear Puzzling, This is a non-consecutive thermo sudoku. Fill the grid so that each row, column ...
Jafe's user avatar
  • 78k
7 votes
2 answers
488 views

A Colombian Jigsaw Sudoku

This is a Colombian Jigsaw Sudoku where the usual rules apply, but with irregular boxes. The dots in the right-hand scheme indicate how many of the numbers in a particular row or column are correctly ...
Xavier Castillo's user avatar
11 votes
1 answer
456 views

One more Colombian Sudoku

Here is one more Colombia Sudoku devised by Xavier Castillo. The usual sudoku rules apply. The dots outside the board above indicate how many cells in the corresponding column or row of that board ...
Bernardo Recamán Santos's user avatar
-1 votes
2 answers
180 views

Sudoku puzzles - best way to learn it? [closed]

What's the best way to learn Sudoku? Are there good websites with methods to do this?
Brendan Darrer's user avatar
2 votes
2 answers
770 views

On solving the minimally clued 8x8 Sudoku

So I have been doing research on the minimal amount of numbers needed to create an 8x8, and found this paper which went over the minimum amount of clues needed for a sudoku to have a unique solution ...
CrSb0001's user avatar
  • 2,413
6 votes
1 answer
325 views

Sudokus with no 3-term arithmetic progressions within

A complete (or solved) sudoku is said to be 3-term arithmetic progression free (3-AP free) if none of its rows or columns contain three terms which are in arithmetic progression (i. e. in none of its ...
Bernardo Recamán Santos's user avatar
14 votes
1 answer
281 views

! ! ! HNY 2024 ! !?

The following puzzle is a typical Sudoku 12 x 12 (1-9, a, b, c), but with an added twist. In addition to the standard rules, each colored box must also contain unique digits; no repetition is allowed ...
Xavier Castillo's user avatar
3 votes
1 answer
99 views

Help with nearly finished expert sudoku

I just started with Sudoku and I jumped directly to a difficult level. I have a hint but don't want to use it. Please provide logic with your answer.
Steve's user avatar
  • 31
13 votes
1 answer
484 views

Happy and joyful 2024!

Fill each empty cell of the board on the left with a digit between 1 and 9. Each box and each column and row must contain all digits. The dots outside the board on the right indicate how many cells in ...
Xavier Castillo's user avatar
15 votes
1 answer
1k views

Yet another Colombian Sudoku

Fill each empty cell of the board on the left with a digit between 1 and 9. Each box and each column and row must contain all digits. The dots outside the board on the right indicate how many cells in ...
Bernardo Recamán Santos's user avatar
16 votes
2 answers
483 views

Another type of Sudoku puzzle

I just found a weird-looking sudoku I left years ago in my basement: I think there was a specific name for this type of puzzle, but I forgot to write it down and now I can't remember it! The only ...
Jujustum's user avatar
  • 3,815
8 votes
3 answers
1k views

What technique can be used to solve this 6x6 sudoku?

Which Sudoku technique can be used to solve this? The screenshot is from the open source Sudoku app by SECUSO (Security Usability Society) for the Android platform.
Rajesh Krishnaiah's user avatar
21 votes
1 answer
1k views

PSE Advent Calendar 2023 (Day 3): 24 dangerous doors

This puzzle is part of the Puzzling Stack Exchange Advent Calendar 2023. The accepted answer to this question will be awarded a bounty worth 50 reputation.< Previous Door Next Door > Task: Solve ...
Lukas Rotter's user avatar
  • 10.3k
1 vote
1 answer
115 views

What is the next logical step I can take when solving the Nov. 30 2023 Sudoku in the Wisconsin State Journal?

Note: sorry for posting this on Dec. 1, but don't worry, I haven't looked at the Sudoku solution yet. So today I decided to try to solve the Sudoku in the Wisconsin State Journal. Now, even though ...
CrSb0001's user avatar
  • 2,413
1 vote
1 answer
88 views

Sudoku variants #2: Lined Numbers (6x6 grid)

Previous variant Today's Sudoku variant is a bit weird. Here's why: Take this screenshot: From this, you might argue that there is nothing that can be logically deduced on this grid. Now you might ...
CrSb0001's user avatar
  • 2,413
0 votes
1 answer
327 views

Sudoku variants #1: Schrödinger's Grave (6x6 grid)

Not in conjunction with my Minesweeper puzzles - that would be concerning! Inspired by Cracking The Cryptic's video "The Graveyard Of Schrödinger" (original gimmick by fjam) How this ...
CrSb0001's user avatar
  • 2,413
0 votes
2 answers
413 views

A 4x4 sudoku shouldn't be that hard, right? Right?

Note: this is not in conjunction with my Minesweeper puzzles Got this idea from one of Cracking the Cryptic's videos, I don't remember which one though. This exact puzzle is still overall unique. ...
CrSb0001's user avatar
  • 2,413
13 votes
2 answers
710 views

A sudokey and 14 messages

This puzzle is part of the Monthly Topic Challenge #15: Multi Puzzle — two (or more) puzzles in one. Remarks: Feel free to post partial solutions. This is a multi-puzzle: If you found the titular 14 ...
Retudin's user avatar
  • 9,248
4 votes
1 answer
268 views

Given an ordinary sudoku puzzle how would you convert it into an irregular sudoku?

I'm trying to create a puzzle like the one below (image snagged from puzzlephil.com). I know how to generate and solve sudoku 3x3 variation via C#, and I'm now trying to add a new variant, irregular ...
BrianLegg's user avatar
  • 143
-2 votes
1 answer
167 views

What are the largest and smallest numbers in decimal base in this special Sudoku?

I have constructed the following hexadecimal 16×16 sudoku in this site: The rules are like 9×9 sudoku tables (each number and letter should repeat only one time in each column, row, and 4×4 ...
Etack Sxchange's user avatar
14 votes
1 answer
747 views

Roughing It (Once More)

This is part 36 of the puzzle series Around the World in Many Days. Each part is solvable on its own. Dear Puzzling, The numbers in blue form a Tapa puzzle. Shade some cells in the grid so that the ...
Jafe's user avatar
  • 78k
7 votes
1 answer
297 views

Next Sudoku Number

Here is a sudoku puzzle coming from this magazine I found that B5 and B6 can only contain 6 and 7. 8 cannot be in B5 because D1 would be a 8 and neither B3 not C1 could be a 8. I thought it would help ...
Olivier Boissé's user avatar
6 votes
1 answer
293 views

Two favorites combined: A Crypto Sudoku

Below is just a plain old sudoku. However, the clues given are a little bit different than usual. It's your job to use them properly. Note: Not every letter makes the same digit, nor every digit is ...
Lezzup's user avatar
  • 7,382
6 votes
1 answer
365 views

Is the Parity Sudoku solvable?

I have a new kind of grid puzzle (you could call it a variant of sudoku) I will be calling a Parity Sudoku. Parity Sudoku is played on a 6x6 grid of integer cells with numbers ranging from 1 to 6. It ...
new Q Open Wid's user avatar
5 votes
1 answer
326 views

Maximize "sudoku" occurrences in a sudoku

How often at most can "Sudoku" occur in a valid (9x9) sudoku? create a valid sudoku replace (all occurrences of) 5 of the numbers by the 5 letters in "sudoku". (and leave the ...
Retudin's user avatar
  • 9,248
6 votes
2 answers
1k views

Can you embed a 4x4 Sudoku inside a 16x16 Sudoku?

In an earlier question (Can a standard Sudoku puzzle contain a miniature Sudoku puzzle?), I asked whether a miniature 4x4 Sudoku could be embedded in a standard 9x9 Sudoku. Inspired by the following ...
Will.Octagon.Gibson's user avatar
12 votes
1 answer
488 views

Sandwiches by the Seaside

This is part 31 of the puzzle series Around the World in Many Days. Each part is solvable on its own. Dear Puzzling, This is a sandwich sudoku puzzle. Each of the eight different letters in the grid ...
Jafe's user avatar
  • 78k
17 votes
2 answers
3k views

Can a standard Sudoku puzzle contain a miniature Sudoku puzzle?

The following is an example of "Miniature 4x4 Sudoku puzzle" in which the goal is to fill each empty square with a number (1, 2, 3 or 4) so that there are no duplicated numbers in any row, ...
Will.Octagon.Gibson's user avatar
7 votes
1 answer
6k views

NYT Sudoku Medium - what does this hint mean?

I have always done Sudoku on paper and can always do mediums and usually hards. I've started doing the NYT Sudoku online and too often have trouble with the medium. At this point in this particular ...
DBeck's user avatar
  • 73
-1 votes
1 answer
137 views

Sudoku android App - Difficulty Level

I have an android sudoku app and I'm doing the following to check if the generated sudoku is unique: Remove a number Run a solver Check if the puzzle is still unique Repeat until solver is unable to ...
Rafail Antoniadis's user avatar
10 votes
2 answers
461 views

Orthogonally connecting even sudoku digits avoiding squares

Is there a way to complete a sudoku where you have to make sure all even digits are orthogonally connected to all the others, while avoiding 2x2 squares of even digits? It is known to be possible when ...
CAN GÜLLÜ's user avatar
11 votes
1 answer
2k views

Can experienced players tell when a Sudoku was randomly generated? Or if it's a shuffled version?

I'm trying to make a simple classic Sudoku game in JavaScript, and I'm wondering what considerations I should have in how experienced players might interpret the generated puzzles. I'm not very ...
bryc's user avatar
  • 321
2 votes
2 answers
243 views

Hard Sudoku: hint for next number

I tried a hard sudoku and I can't figure out what the next number is. I tried some online tools without any success (I don't want to have the final solution without any explanation). I would be very ...
Olivier Boissé's user avatar
1 vote
1 answer
226 views

Explanation why next cell has to be a certain value

I'm an absolute beginner and was stuck at the first puzzle of Sven's Sudoku Pad. I reached the following board state, where I noted for every cell which values were possible: After a while I simply ...
Felix Schön's user avatar
4 votes
1 answer
291 views

Why can't a 1 go in this field

I've moved onto "expert" sudoku's in my app (Sudoku.com on IOS) and whilst I am getting by solving some, others I'm having a hard time with. With this one, I used a hint so the AI could note ...
webnoob's user avatar
  • 151
12 votes
1 answer
398 views

Behind Great Walls

This is part 10 of the puzzle series Around the World in Many Days. Each part is solvable on its own. Deаr Puzzling, This is a word search puzzle with a wildcard character. There are eight unique ...
Jafe's user avatar
  • 78k
13 votes
1 answer
942 views

Horological Horrors

This puzzle is part of the Monthly Topic Challenge #6: Is it really that [time] again?. I was visiting my grandfathers workshop one day, when he received a call and had to run out for a bit. He told ...
gabbo1092's user avatar
  • 6,000
8 votes
2 answers
580 views

How many Nonconsecutive Sudoku solutions are there?

Consecutive Sudoku is a variant with the additional rule that orthogonally adjacent numbers are consecutive if and only if there is a dot/bar on the line between them. A Nonconsecutive Sudoku is one ...
bobble's user avatar
  • 10.4k
7 votes
1 answer
663 views

Unsure how to continue Sudoku solve/apply Y-Wing strategy

I am not new to solving a sudoku board, but I do not have a lot of experience with harder boards and more advanced strategies (I am able to solve a "hard" board in under 10 minutes, on ...
kaitlynmm569's user avatar
  • 1,329

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