# 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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### Ever heard of a W-Sudoku?

You may have heard of a type of Sudoku called an XV-Sudoku. In such a Sudoku, cells connected with an "X" must sum to 10 and cells connected with a "V" must sum to 5. In this W-...
153 views

### Sudoku Logic From Another Planet

This is the brutally hard Tatooine Sunset Sudoku puzzle by Philip Newman ... except the Noble Happy Star has goofed! Two of the digits have been swapped and there are multiple solutions. Fortunately, ...
181 views

### Suko-kulink (Sudoku, Suko and Slitherlink tri-brid)

Rules: The lower part of the puzzle is a sudoku. Basic sudoku rules applied. The upper and right of the puzzle are suko puzzles. The numbers in circle and to the selected square has the same number ...
99 views

### Sudokus everywhere 2

Every 9x9 box is a valid sudoku, making 4 sudokus in all. Hopefully this one is a little more challenging than the previous one. I tried keeping the clues symmetric, but didn't quite manage. Enjoy!
3k views

### Sudoku like you've never seen it before

I've spent this week trying to create a difficult logic puzzle which is a combination of two Sudoku varaints, 'Samuari Sudokus' and 'Pseudokus', and this combo is unlike anything you can find online. ...
761 views

### Sudokus everywhere!

Every 9x9 box is a valid sudoku, making 9 sudokus in all. I'm not sure how hard it is as I started solving it with just a few clues, then added more whenever I got stuck. Enjoy!
411 views

### A sudoku with only four given digits and some more rules

Ok so this is one of the hardest sudokus (and one of the best sudoku) I have ever seen, with only $4$ given digits. There are some more rules too :- $(i)$ First, normal sudoku rules apply here. $(ii)$ ...
464 views

### An odd looking Sudoku

Somewhat in the spirit of Stiv's This new puzzle type needs a name, can you solve this odd looking Sudoku and give it a name?
241 views

### Hero Wars RPG - The Sudoku!

In the popular online action RPG game Hero Wars, the player has to solve some simple but fun puzzles to win loot such as weapons and cash ā assuming the incessant ads Iāve seen on Facebook are all ...
123 views

### Are there Sudokus that are so hard that no known logical deduction techniques can reduce it? [duplicate]

Are there Sudokus that are so hard that no known logical deduction techniques can reduce it? Maybe such a technique would reduce away multiple options?
274 views

### No Numbers Sudoku: The Ball of Queens

Those are all of the numbers you need. No, I did not forget any. Normal sudoku rules apply. All numbers, except for 1's and 9's, are queens with respect to themselves. E.g. 2's have the queen's ...
201 views

### Will forcing chains break this sudoku puzzle?

I am trying to pick up advanced sudoku techniques by practicing with ādifficultā puzzles as suggested by my sudoku app. In this puzzle, I am stuck in the position as shown below. I think I can make ...
331 views

### Does “naked set” method always solve a sudoku?

Is always possible to solve a sudoku (that has a unique solution) using only naked pair/triple/quad methods? If not, what about using naked set and hidden set methods combined togheter? I need to know ...
306 views

### Can someone solve this sudoku without trial and error?

I'm stuck on this sudoku. If anyone can solve this, then please share and explain the method that you used.
2k views

### Sudoku medium difficulty help

I keep getting stuck on the NY Times Sudoku medium difficulty puzzles. I go through one number at a time and narrow down large box where that number can only be in two spaces. When I finish the nines ...
989 views

### Sudoku Help: Hard

I am unable to finish this Sudoku. All numbers are verified by the app. I'm sure there must be a way to solve this without guessing. Even an online tool couldn't tell me a next number.
47 views

### Is there a sudoku app where the hint identifies the squares/logic to use to solve the next step?

I have an app that has different levels of sudoku puzzles and I'm trying to learn to solve Expert. The app I'm using has a hint function, but all it does is fill in the correct answer in a selected ...
551 views

### How to see why single candidates are obviously correct?

I am trying to understand something that should be simple. I have a "easy" puzzle here, and immediately found where 8 should be in the middle box. But in various Sudoku Apps, they show &...
105 views

### A slightly different type of Sudoku puzzle

The following image shows two valid Sudokus. The first was copied verbatim off Wikipedia, and the second was obtained by rotating 90 degrees. Any two distinct valid Sudokus must differ in at least ...
352 views

### How to Trap Your Moderator

You have locked your least favorite moderator behind a 27x27 Sudoku... Now you regret, but you have forgotten how to solve the puzzle... CSV version: ...
441 views

### Tribute to a Great Mind

This is a puzzle based on an existing Sudoku problem composed by someone else. There are nine regions and each row/column/region must contain the same set of nine different letters: {G, R, E, A, T, M,...
984 views

### Sudoku in the third dimension (3D Sudoku)

People seemed to enjoy my last Sudoku variant puzzle - Samurai Pseudoku, so I spent this week making another! This one is going to require using logic you've never used before... The last one was a ...
247 views

### Compoundoku wants REALLY BIG!

Rules of Compoundoku: Solve both left and right Sudokus. In addition, the board below them is the Compound Board of both Sudokus. Each number on the Compound Board should tell either: (1) the number ...
325 views

### The Existence of Total False Sudoku

Is it possible to construct a valid $9 \times 9$ puzzle of Total False Sudoku? Total False Sudoku is a regular Sudoku puzzle where all given clue numbers are wrong. A valid puzzle is a puzzle that ...
252 views

### Arithmetic Progression Sudoku

In this puzzle, each square must contain a positive integer. All rows, columns and boxes must contain an arithmetic progression of length 9. Good luck!
544 views

### Knights of the Square Sudoku Table

8 . . | . . . | . . 6 . . 4 | . . . | . . . . . . | . . . | 9 1 . ---------+---------+-------- . . . | . 2 . | . . . . . 9 | 3 . . | . . . . . . | . . . | . ...
396 views

### Square Number Sudoku

Solve this diabolic Square Number Sudoku. Normal Sudoku Apply. Additionally, there are some rectangled area, in each area should be read as 1 number. The numbers must be SQUARE NUMBERS. There are: 1 1-...
347 views

### Monument Valley Sudoku

Another Sudoku monstrosity from the brains of Yours Truly. No rules are given, part of the challenge is trying to work out what the rules are :)
379 views

### George Orwell Sudoku

Here is a puzzle I created today. The title is "George Orwell Sudoku" Normal Sudoku rules apply. In every coloured group of three cells the middle digit must equal the sum of the other two ...
637 views

### A Minesweeper Sudoku

My brother created this puzzle, and he wanted me to post this here. Each 3x3 box contains three mines (those squares also have numbers in them). There are no mines in boxes containing a 1, 2, or 3. ...
1k views

### Largest cages Killer Sudoku

Task 1: Find the maximum value of $n$ for which it is possible to create a regular uniquely-solvable Killer Sudoku (9x9) such that every cage has atleast $n$ cells in it. Rules for killer sudoku ...
742 views

### How can this puzzle be solved without guessing?

This puzzle was given to my 8 year old from the school. My child was struggling, so I gave it a bash, but was unable. I do sudoku regularly so know most methods of solving. I gave it to my husband and ...
115 views

### stucked really bad with sudoku puzzle

Stuck with this for long time now, I have tried all the techniques yhat I know
169 views

### How to test a sudoku solver?

I have created a standard sudoku solver using my own algorithm. It relies on a continuous scanning with occasional tuple/pair searching. I am looking forward to test if this works properly. I have ...
118 views

### Stuck with sudoku

Stuck with this for long time now, applied all the techniques i can think of Blank: All possibilities: missed 6 as possibility in R8C5 Verified that this has unique solution
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### A 16 Clue Sudoku Puzzle (but the kings can't be in check)

An entry in the 19th fortnightly challenge... Above is a 9x9 "chess" board with some pieces already laid out, your goal is to fill the board completely, following standard Sudoku rules (i.e. every ...
163 views

### Help with Sudoku

i recently was playing sudoku on my iPad. As i was stuck on the puzzle i tipped on "Tip" to receive a hint on how i can solve this sudoku (I am still learning the game) - so please don't judge me for ...
576 views

### Multiplicative sudoku (donāt use computers please)

If I place all the numbers from 1 to 9 in a 3x3 grid and I add the products of each row and column, then what is the minimal and the maximal sum? For example, the sum is 450 on the picture above
302 views

### How many unique “miracle sudokus” are there?

The following "Miracle Sudoku" puzzle contains only two starting numbers, plus some additional rules that end up revealing the whole board: https://www.youtube.com/watch?v=yKf9aUIxdb4 (or Sudoku ...
1k views

### Sudoku variation: Using various chess moves, solve the grid from just two numbers

I've been watching a youtube channel hosted by puzzlers and attempting the sudoku variation they post each day. Today's I found particularly interesting and while sharing it around it proved quite the ...
4k views

### What if I told you that guessing in Sudoku is very bad and might give you a bad karma?

Yesterday, I tried to solve a regular Sudoku puzzle. Of course, the Sudoku puzzle had a unique solution. But, I was feeling a little lazy, so, rather than solve the puzzle properly, I made guesses! At ...
475 views

### Sudoku: Stuck, Need hint to move forward

I have applied the techniques I know to eliminate possible candidates. I'm stuck at this stage now, any hints to move forward are appreciated. I found this puzzle in Microsoft sudoku Android app.
254 views

### Next move for Sudoku puzzle and why [closed]

I am currently stuck at this point in the below Sudoku puzzle. I have tried to apply various tricks such as XY wing, swordfish etc. but the preconditions are not fulfilled for any number. What is my ...
144 views

### Smudged Sudoku - help me solve it!

One late evening I was making my sudoku. I finally finished until water spilled all over the middle-right block. The only thing I remember is the numbers present in the block (but not their position):...
1k views

### Tic tac toe - Sudoku: A variation in which the centre box defines the layout of the other boxes

I stumbled across this interesting variation of Sudoku the other day and thought I'd give it a try, it has however baffled me and I've been unable to progress past the very early stages. The puzzle ...
817 views

### Knights in a Complete Sudoku Board

In a complete Sudoku board, at most how many chess knights would it be possible to place on its cells with a 1 inside, so that each knight can walk in order (1, 2, 3, ..., 9) through cells numbered up ...
142 views

### Minimum number of clues required for a 16 x 16 Sudoku

It is well-known that the minimum number of clues that completely specify a 9 x 9 Sudoku is 17. What is the minimum number of clues required for a 16 x 16 Sudoku whose cells contain one of the ...
194 views

### Puzzle of the day - three in one Sudoku?

A three in one sudoku. Have fun