# 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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### Sudoku board position hint

As the title says, I'd like a hint (and an explanation why it is so) for the puzzle position in the attached image. I think I'm missing something really obvious but I can't figure it out. Again ...
467 views

### Revenge of the Cryptic Crossword Sudoku

This puzzle is inspired by Matt’s excellent Cryptic Sucrosswordoku. Below is a sudoku as well as some cryptic clues. The clues lack enumeration and are in no relevant order. The solutions to the ...
395 views

### Cryptic Crossword Sudoku

This puzzle is inspired by Matt’s excellent Cryptic Sucrosswordoku. Below is a sudoku as well as some cryptic clues. The clues lack enumeration and are in no particular order. The solutions to the ...
1k views

### Cryptic Sucrosswordoku

Maybe I'm a little bit evil. I've combined a couple of puzzle types in a novel way (to me, at least). I'll lay down some rules. The solution to the sudoku works exactly the way a normal 9x9 sudoku ...
322 views

### What am I telling to you?

For my first question here, let's start cool with a little sketch. No, it's no hard brainstorming, no, it's not a revolution, yes, I had to start with something :)
722 views

### Algebra Sudoku: Dozens

Alas, the grid deduction fortnightly is over, but my love for the genre remains the same - i.e. very high. So, here is another grid deduction puzzle. An algebra sudoku! I think the rules are fairly ...
1k views

### Sum in A Sudoku

Color Blind version: Here's a sudoku puzzle with a twist! The numbers given in the squares are actually the sum of the numbers in that region. For example: 18= Sum of the numbers in the 4 yellow ...
270 views

### What is guessing? [closed]

The whole difficulty of solving puzzles like sudoku is doing it without guessing. Well, either without any guessing whatsoever or with little enough that a human can still make retractions and come to ...
2k views

### Empty sudoku puzzle

The rules are the same as for a normal sudoku puzzle. The only thing different is that instead of numbers for clues, you have greater than/less than (> <) signs between the cells. Have fun solving!...
750 views

### Happy 2017 Sudoku

This is a simple Sudoku. The only thing different from a regular sudoku are the symbols used: HAPY2017*. The snowflakes (a.k.a. asterisk) are like any other character. Wishing you a Happy New Year ...
4k views

### A Page of Puzzling

I found this puzzle page from a newspaper and found it absolutely confounding. The sudoku had question marks and other things all over it, the logic puzzle made no sense, the cryptic crossword was ...
1k views

### Christmas Sudoku

CHRISTMAS IS COMING!!! And to celebrate, here is a Christmas related sudoku: *A friend gave this to me and it took a long time for me to solve it. Thaks to @GentlePurpleRain for providing an updated ...
1k views

### There is a reason sudoku uses squares

There exists a 9x9 grid with the cells in one single row numbered 1-9 in order. The cells in the other 8 rows are initially empty. Note: The cells initially containing numbers can be in any one row;...
4k views

### Techniques to Solve this Sudoku Puzzle

I have a sudoku puzzle seen below that I am trying to solve. I know I can punch this into some sudoku solver and get the answer but I am looking for techniques I can use to solve this. Any advice?
210 views

### What is wrong with this Sudoku Game?

Before you, you have a game. There's something wrong with this game. Can you figure out what it is? ...
778 views

### Help me to decorate my Christmas tree

Help me to decorate my Christmas tree with garlands of 7 bulbs. I want to fill in all the blank bulbs with numbers 1 to 7, so that each garland contains 7 different numbers. To make the tree more ...
2k views

### 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 ...
445 views

### Sudoku as Poetry: A Tag-Fusion Masterpiece

This is an entry in the 19th fortnightly topic challenge: Unconventional Tag Fusion. I wrote some poetry for you, but it's hidden within this sudoku. Solve the puzzle and find the poem. For those ...
985 views

### Why is this Sudoku Skyscraper Failing?

I'm attempting to write a program that solves Sudoku puzzles using a variety of techniques. Up this point, I've only implemented naked singles and hidden singles (for rows and columns). I've been ...
2k views

### Can you solve the 7x7 (sudoku-ish) centered sums puzzle

I have come across this puzzle a few times in competitions and rally's, and it has troubled me because I cannot seem to find a good approach to solving it, either programmatically or numerically. And ...
2k views

### When Sudoku met Ratio

Continuing on from my previous sudoku... I found an old piece of paper with a sudoku solution on it and vaguely remember solving it. This is unlike a simple solution however. You get no starting ...
424 views

### An enigmatic sudoku

I entered the dungeon through a small, dark tunnel. After a seemingly endless walk I finally reached a small room. At the other side of the room, there was a big iron door. And in front of the door, ...
900 views

### Hexagon (Sudoku-like puzzle)

This is the hexagon with digits to each row and diagonal which follow the rule : If the row and diagonal contains 5 triangles, it must contains all of the digits from 1 to 5. If the row and diagonal ...
33k views

### How do I solve the world's hardest sudoku?

This question is posted under the guidelines Don't worry too hard about restricting or regulating anything that isn't turning into a problem yet. If you don't agree that this question is on topic, ...
742 views

### Historical figure sudoku

This sudoku hides a famous person from the past. A solution will be accepted if the sudoku is solved (with steps to solve). The letters used are: abceloprt (in alphabetical order). PS. ...
1k views

### Alphabetical Sudoku

Who loves fish? Okay that might sound a bit weird but don't worry, I am still sane. Maybe. To answer the question you must complete the Sudoku below. A word will appear in the highlighted box which ...
617 views

### Sudoku solving strategy

I started solving the puzzle below and I got stuck at this point. I don't know how to continue solving this puzzle except using try and error. Does anyone know of a strategy to solve it?
3k views

### What is the maximum number of empty 3x3 blocks a proper Sudoku can have?

It is possible to have a proper Sudoku with one empty block (consisting of 3x3 cells). The trivial (and very boring) example would be a puzzle where all other cells are given. It's impossible to have ...
873 views

### Non brute-force Sudoku

The mypuzzle.org site (Difficulty = Hard, Date = 2016-07-12) has the following Sudoku puzzle. I filled in a three easy cells (in square brackets) but then got stuck. Aside from brute force, is there a ...
2k views

### The Unfinished Puzzle Section

Simply complete the sudoku and crossword, happy puzzling. Across 1. Achieved acclaim by being knowledgable about strange apron (3, 6) Down 2. Explode asteroid five to refrain from inactivity or ...
252 views

### Amazing sudoku who can find hot numbers

Sudoku X Place the numbers 1-6 once in every row, column, diagonal, and 3x2 block. The diagonals form an X and are highlighted. Puzzle Text of puzzle ----------------- | . . . | 5 . . | | . . . | ...
902 views

### Single solved state for Sudoku Pyraminx

(Not sure if this is the correct stackexchange, but I think it is.) I recently bought 10 QJ Pyraminxes with an ambitious idea for a mod in my head. After just the first step of modding I realized it ...
4k views

### Check sudoku solvability

With a blank grid, I put and number (1-9) any cell, the Sudoku has n solutions. I continue filling any blank cells with numbers that satisfy the constraints, so the Sudoku still has many solutions, ...
880 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 ...
1k views

### Can you solve my Chess Sudoku puzzles?

Rules Normal Sudoku rules apply except that instead of 9s you must place chess pieces. A puzzle can mix chess pieces, and in principle any piece may be used - although the rest of the constraints ...
192 views

### Mastering Sudoku? [duplicate]

I have been solving sudoku for years but this one is the hardest of all that I have ever completed. It took me 2 weeks to complete it. Here it is TRY AND SOLVE:
2k views

### Creating a solved 9x9 Sudoku based on certain rules

The question: A rectangular fence is a set of 4 cells on a solved sudoku grid with co-ordinates $(i,j)$, $(m,j)$, $(m,n)$ and $(i,n)$. You can visualize this as the 4 corners of a rectangle. ...
259 views

### Empty Rectangles - Does the rule apply when the intersection takes place inside the box with the empty rectangle?

The Empty Rectangles method is a strategy for solving Sudoku puzzles. I have seen the description of this strategy here, I have the following question: Is there a problem if the other end of the ...
605 views

### What is the fewest number of clues on a rotationally symmetrical sudoku grid with a unique solution?

It is known that the minimum number of clues a sudoku must have to have a unique solution is 17. But on every website I've seen for them, I haven't found any that are rotationally symmetrical. I once ...
954 views

### How to check a partial sudoku solution

John has started a sudoku puzzle and shows me his completed work, asking whether he's made any errors. There are no obvious errors (a number repeated in a row or subgrid). I know of two ways to ...
202 views

### Sudoku: need a traceable hint for the next number

Partially solved sudoku: ...
501 views

### Reasoning behind next step in sudoku

As you can see in the image, I've been struggling with this sudoku for quite some time and I'm completely stuck. I'm sure I'm missing one standard trick which would make it easy to solve, but I can't ...
267 views

### RELATIONS: Introducing the Sudokross

Behold my sudokross!                           Similar to sudoku, the objective is to fill every row and every column with the ...
659 views

### Sudoku Puzzle, What's My Next Move and Why?

I currently have a sudoku puzzle that looks like this: ...
6k views

### Removing numbers from a full sudoku puzzle to create one with a unique solution

What is a simple and efficient way of removing numbers from a full sudoku puzzle to create one with a single unique solution? I have already figured out how to generate sudoku grids, like this one: <...
920 views

### Devising a sudoku where the rows are the moves for a draw in tic tac toe

The task is to construct a sudoku whose rows (or columns) are the moves for a game in tic tac toe where the game ends in a draw. Here are some clarifications and constraints which should limit ...
228 views

### Sudoko-net pseudo-solvable with minimum blocks

A sudoku net is defined here. A sudoku net is defined as 'pseudo-solvable' if we can deduce at least two valid 'not unique' solutions . friendly sudoko is defined here What is the sudoku ...
234 views

### How does one make a program to provide all the 'possible' numbers in an empty cell

To be able to solve a sudoku one usually has to first work out all the 'possible' numbers in an empty cell. How can one make a program to do this? In this case 'possible numbers' are ones which have ...