Sudoku Puzzles

Number of 9×9 Sudoku solution boards:
6,670,903,752,021,072,936,960

Number of different 9×9 Sudoku solution boards:
(eliminating symmetries such as rotations)
5,472,730,538

Sudoku rules are simple enough. Arrange the numbers such that the 1 to 9 appear in each of the nine:

3x3 regions as delineated by the light blue and green shading
rows
columns

Completing the Sudoku board is not so simple. Trial and error is one approach that may or may not solve Sudoku puzzles. However, trying that approach may lead you to see patterns or to develop your own insights and strategies for solving Sudoku puzzles. Beyond that, there are books and many articles on the Internet explaining how to solve Sudoku puzzles.

Sudoku Puzzles to Solve is my implementation for generating Sudoku puzzles. The program to generate Sudoku solution boards is written in the C programming language and runs on my local computer. The program generated Sudoku boards provide all the data I need to generate Sudoku puzzles in the web application.

The C program was actually written to solve Sudoku puzzles. The generation of Sudoku puzzles is just a by-product (having the program solve a blank puzzle generates solution boards). The program execution is a combinatorial exercise which is very computationally-intensive. On my computer, with my present recursive algorithm (with backtracking), I am able to solve up to 16x16 Sudoku boards.

Sudoku Abuse!