The Stack Overflow podcast is back! Listen to an interview with our new CEO.

# 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.

169 questions
Filter by
Sorted by
Tagged with
203 views

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

Partially solved sudoku: ...
508 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 ...
278 views

### RELATIONS: Introducing the Sudokross

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

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

I currently have a sudoku puzzle that looks like this: ...
7k 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: <...
923 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 ...
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 ...
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 ...
878 views

### How to generate and count the 7x7 Latin squares

How many 7 by 7 Latin squares are there, and how can one generate examples of them? I am working on classes for a game, and typing in numbers manually from 1-7 in rows and columns from scratch is ...
2k views

### Magic Squares in Sudoku Grids

A 3x3 magic square is a 3x3 grid containing the numbers 1-9 once each, and in which every row, column, and diagonal sums to 15: 294 753 618 And I presume we all ...
877 views

### Pseudoku: A Game of Finding Order in Chaos

You are Pat Doe, a lowly Sudoku puzzle-maker eking out a living by producing hand-made Sudoku puzzles. After an exhausting eight hours, you've just completed your last Sudoku grid for the day. ...
252 views

### Non-Diagonal Pointing Problem

You can see the rules for pointing problem at this article. It has been clarified that there is no solution to this question. But, what if we remove the diagonal rule? is there any solution?
709 views

### SuDoKu Unique Rectangles and the “2 blocks” rule

On HuDoKu's page on Uniqueness, under Unique Rectangle, it says A common mistake when looking for URs is to violate the "2 blocks" rule (see the Sudopedia article for an example). Unfortunately, ...
684 views

### How do I necessitate the use of the X-Wing pattern during Sudoku creation?

I want to create a Sudoku puzzle, and I want it to be of moderate difficulty. There's a specific pattern I want to include, called the X-Wing pattern: This occurs when two numbers form locked ...
2k views

### Why must a sudoku have a unique solution [closed]

Why must a sudoku have a unique solution. In my books I don't guarantee it. But I am sure there are not many which don't. I doubt if one in a thousand dont have. And even if they don't its only a ...