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Sudoku - Questions and Answers



Why was written?
The two freely available products mysql and PHP: Hypertext Preprocessor are widespread and accepted. Purpose of the project Sudoku was to learn the utilisation of both.
Furthermore, to create PDF (Portable Document Format) documents, the freely available PHP class fpdf was used.
Thanks to programmers of this excellent software.

Where the Sudokus come from?
I wrote a code in Visual Basic based on Microsoft Excel in the course of a previous project. This generates and/or solves Sudokus. All displayed puzzles are calculated by this program.

How is the quality of the Sudokus?
Each Sudoku has exactly one solution. The puzzles are calculated according to coincidence principle without use of any archetype. Of course the Sudokus are compared with each other (incl. rotations and mirrorings). With that, each is guaranteedly unique. Beyond doubt the quality is better than that one of many Sudokus printed in journals.

How was the level of the indicated Sudokus calculated?
Every puzzle is based on the minimum number of set digits. Meant that, a further number is removed, more than only one solution is possible. This results in the level Very difficult. For all other difficulties additional digits are set:
Difficult: 4 digits
Moderate: 8 digits
Easy: 12 digits

What is the advantage of the registration?
As registered user it is possible to input solving times or to mark Sudokus as solved. These puzzles are not displayed to the user anymore in future.

What is required for the registration?
The only condition for the registration is a valid mail address. The password is automatically generated and sent.

Which programs are used on the computer of the user?
To display the PDF (Portable Document Format) an appropriate software is presupposed. This can be downloaded for free at PDF (Portable Document Format).

Which enlargements are planned?
Introduction of user related statistics (e.g. the comparing of the solution times with those of other users).
Introduction of a site for the simultaneous entering of several results for logged-in users.
Introduction of a site to generate automatically new Sudokus.