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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1answer
109 views

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 ...
3answers
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 ...
2answers
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 ...
3answers
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 ...
1answer
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 :)
1answer
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 ...
1answer
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 ...
1answer
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 ...
1answer
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!...
2answers
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 ...
9answers
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 ...
1answer
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 ...
3answers
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;...
2answers
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?
2answers
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? ...
2answers
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 ...
2answers
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 ...
1answer
446 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 ...
1answer
987 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 ...
2answers
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 ...
4answers
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 ...
1answer
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, ...
1answer
901 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 ...
4answers
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, ...
2answers
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. ...
2answers
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 ...
1answer
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?
3answers
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 ...
2answers
876 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 ...
6answers
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 ...
2answers
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 . . | | . . . | ...
3answers
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 ...
1answer
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, ...
2answers
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 ...
2answers
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 ...
0answers
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:
3answers
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. ...
1answer
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 ...
2answers
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 ...
2answers
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 ...
1answer
202 views

Sudoku: need a traceable hint for the next number

Partially solved sudoku: ...
2answers
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 ...
1answer
267 views

RELATIONS: Introducing the Sudokross

Behold my sudokross!                           Similar to sudoku, the objective is to fill every row and every column with the ...
3answers
659 views

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

I currently have a sudoku puzzle that looks like this: ...
2answers
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: <...
2answers
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 ...
2answers
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 ...
2answers
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 ...
1answer
1k views

Self-referential Sudoku

I built this a while back but never had a good forum for it; this seems like the perfect spot to turn it loose. This is a 'traditional' Sudoku; cells are filled with numbers from 1 through 9, and all ...
2answers
1k views

Hardest sum sudoku ever! (as well as how to solve them)

This sum sudoku is probably the hardest puzzle I've ever encountered, and I have made very little progress (a few cells or so). I found it in a book by Reader's Digest. The solution is given, but ...