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Sudoku Solver

Tool/Solver to resolve sudoku/wordoku grids (directly or step by step). The aim of the sudoku game is to fill the rows and columns of a 9x9 grid with each digit only once.

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Sudoku Solver -

Tag(s) : Number Games

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# Sudoku Solver

## Solve a sudoku grid

 Resolution Compute all solutions Step by Step Solution

Tool/Solver to resolve sudoku/wordoku grids (directly or step by step). The aim of the sudoku game is to fill the rows and columns of a 9x9 grid with each digit only once.

### How to fill the Sudoku grid?

Make a copy/paste or type directly in cells. Letters (Wordoku/alphadoku) and digits are accepted.

Example: Copy the Sudoku content in the first cell (top left) 97 1 5 5 9 2 18 4 8 7 26 92 3 6 2 9 19 4572 to get :

 9 7 1 5 5 9 2 1 8 4 8 7 2 6 9 2 3 6 2 9 1 9 4 5 7 2

### How does the step by step works?

Software solves the Sudoku like an human and display each step of its progress to understand.

Sometimes the reasoning stops at a step where no logical deduction can deduce at 100% the value of a box (several possible values). The solver performs a random pick among these possible values and continues, if an inconsistency occurs (the sudoku turns to have no solution) then it goes back to the step of the random pick and choose another value. To maximize the chances, choose a number which, if it is positioned in the cell, will allow the maximum of deduction in the continuation of the sudoku.

If the program indicates that there is only one possible value, it means that no other value is acceptable in the box.

### How to test if a sudoku has a unique solution?

dCode calculates all the solutions for the sudoku, not only the first one. To check a homemade sudoku, the solver can confirm that there is only one solution.

### When Sudoku have been invented?

The first Sudoku versions are from 1979

### How many distinct sudokus exist?

A line can consist of $9!$ (Factorial of 9) different ways, but the whole sudoku has a number of possibilities much less than $9!^9$, because some permutations can lead to identical grids. The total number of grids would be $9! \times 72^2 \times 27 \times 27 \times 704267971 = 6670903752021072936960$ combinations.

### Does a rectangular sudoku or non square sudoku exists?

By keeping the sudoku NxN rules that require the N characters to be used on each row and column, then it is impossible to respect them if the sudoku is not square.

Some variants of the square sudoku, however, use non-square inner blocks (see sudoku 6x6, sudoku 7x7 or sudoku 8x8)

## Source code

dCode retains ownership of the source code of the script Sudoku Solver online. Except explicit open source licence (indicated Creative Commons / free), any algorithm, applet, snippet, software (converter, solver, encryption / decryption, encoding / decoding, ciphering / deciphering, translator), or any function (convert, solve, decrypt, encrypt, decipher, cipher, decode, code, translate) written in any informatic langauge (PHP, Java, C#, Python, Javascript, Matlab, etc.) which dCode owns rights will not be released for free. To download the online Sudoku Solver script for offline use on PC, iPhone or Android, ask for price quote on contact page !