Questions tagged [sudoku]

This challenge is directly related to solving, creating, or otherwise working with sudoku puzzles.

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20
votes
13answers
4k views

Implement a Brute Force Sudoku Solver

Implement the shortest Sudoku solver using guessing. Since I have received a few request I have added this as an alternative question for those wishing to implement a brute force sudoku solver. ...
9
votes
3answers
3k views

Build a Killer Sudoku Solver

You thought regular sudoku was hard, now try Killer Sudoku! In the game of Killer Sudoku, you aren't given any numbers at all. Instead, you're given regions that are said to add up to a certain ...
20
votes
8answers
2k views

The fastest Sudoku solver

Winner found It seems as if we have a winner! Unless anyone plans on contesting the world's current fastest Sudoku solver, user 53x15 wins with the staggeringly fast solver Tdoku. For anyone still ...
-2
votes
1answer
226 views

Morse sudo-ku-de

Hehe, see what I did with the title? Anyways... Your job is to create a sudoku solver that accepts input in Morse code and creates output in Morse code. Here's the Morse code numbers for reference: <...
16
votes
1answer
436 views

Maximize Sudoku King's tour

Background Sudoku is a number puzzle where, given an \$ n \times n \$ grid divided into boxes of size \$ n \$, each number of \$ 1 \$ to \$ n \$ should appear exactly once in each row, column and box....
26
votes
25answers
4k views

Output a Sudoku board

Today's challenge is simple: Without taking any input, output any valid sudoku board. In case you are unfamiliar with sudoku, Wikipedia describes what a valid board should look like: The objective ...
0
votes
0answers
133 views

Validate Sudoku (N by N) [duplicate]

Challenge : Create a random (pseudo random) Sudoku board with dimension n x n Input : Given : ...
8
votes
4answers
625 views

Find the rows which make each column have one True (was: Knuth's Algorithm X)

Task Given a Boolean matrix, find one (or optionally more) subset(s) of rows which have exactly one True in each column. You may use any algorithm, but must support very large matrices, like the last ...
19
votes
1answer
982 views

Unique Sudoku Finder

Challenge: Given a Sudoku board on standard input, find the minimum number of numbers added to make the board unique. Specifics/Rules: The input is formatted as follows (all whitespace is ...
21
votes
20answers
5k views

Create a sudoku solution CHECKER

Create a Sudoku solution CHECKER There are oodles of Sudoku SOLVERS here, but I want you to create a solution CHECKER as small as humanly possible (code-golf). A valid entry will be able to either ...
65
votes
7answers
5k views

Regex Golf: Verify a Sudoku Solution

Write a regex which matches any valid sudoku solution and doesn't match any invalid sudoku solution. The input is an unrolled version of the sudoku, i.e. there are no line delimiters. E.g. the ...
16
votes
4answers
852 views

Build a minimum-clue Sudoku unsolver

My attempt at stating this question, but with a more objective solving criterion. Your task is to build a program or function that takes a solved Sudoku grid S in ...
8
votes
5answers
384 views

Retrieve all possible marks that can be placed in a Sudoku puzzle [closed]

Given a Sudoku puzzle, find all possible marks that can be filled into each empty cell. Test case Input: ...
7
votes
1answer
343 views

Create a diagonal sudoku board

A Diagonal Sudoku board is a special case of Latin squares. It has the following properties: The board is a 9-by-9 matrix Each row contains the numbers 1-9 Each ...
27
votes
2answers
3k views

Implement a Non-Guessing Sudoku Solver

Implement the shortest Sudoku solver. Sudoku Puzzle: ...
11
votes
2answers
461 views

Y-Wing Strategy for Sudoku

I recently got a new Sudoku app that produces really hard Sudoku's, which can't be solved using the standard strategies. So I had to learn a few new ones. One of these strategies is the Y-Wing ...
35
votes
14answers
6k views

Sudoku Compression

Your job is to write a program (or two separate programs) in any language that: Can take a completed Sudoku board as input (in any logical format) and compress it into a string of characters Can take ...
9
votes
0answers
1k views

Minimal Sudoku Generator [closed]

Ask questions if you need to, I'll elaborate on anything that needs clarified. My challenge is to unsolve a sudoku to a minimal state. Basically take a supplied, solved, sudoku board and unsolve it ...
10
votes
1answer
1k views

How many Sudoku puzzles exist?

This is not a Sudoku solver, nor a Sudoku checker. Your challenge is to write a function or script that, given as input the "block" size of a 2D Sudoku puzzle (which is 3 for the classic 9x9 board, 4 ...
6
votes
1answer
2k views

Sudoku board generator

A program that randomly generates a Sudoku game board with varying degrees of difficulty (however you decide to measure difficulty). Sudoku requires that there is only one solution, so your program ...