Sudoku generator

Lunatic · Posted: Mon Apr 14, 2008 10:27 am Post subject: Sudoku generator

[EDIT]Latest version available - October 6th 2008[END EDIT]
For anyone interested, i've been updating my pattern based sudoku generator recently and is now downloadable, just click here. Visual Basic source code is available too.
Since there's no Help file, i will provide some information here...

This is the interface:

How to generate sudokus:
-Choose a base pattern (using "Next" or "Previous" buttons, or create a new one by toggling the cells on/off with the mousecursor. The red cells are those where the givens are to be generated.
-Choose the required modifications, there are only a few modifications possible. The first one, 'Random patterns' will force the generator to randomly choose a pattern (from those in the database) for each sudoku that is to be generated. The second option 'Limited to "Very Hard"' will limit the generated sudokus to the "Very Hard" level. With the third option you can make the generator try to expand the base pattern with 1, 2 or 3 extra givens which will only occur if the base pattern has multiple solutions making attempts to find a unique solution. By default, this option is set to "Don't expand, seek sequential". This default option will seek for the first unique sudoku from a maximum of 250 sequential attempts based on the first randomly generated givens. If no unique sudoku is found within 250 attempts, the givens are randomly regenerated, and so on. You have the ability to change the number of sequential attempts.
The last option is for checking the generated sudokus if they are minimal, this means that all clues are needed to have a unique solution. There's a similar option for testing sudokus on uniqueness.

The whole generator is based on my pseudo-dancing links brute force solver written in Visual Basic. See topic "DANCING LINKS and VISUAL BASIC"

The patterns have some restrictions...
-a minimum of 20 givens is required
-more than one empty row within the same band is not allowed
-more than one empty column in the same stack is not allowed
-more then four empty boxes are not allowed

About the randomly generated givens...
-the given cells are adressed in random order (by using a randomly re-ordered GivenMap-array)
-each given cell will recieve the available candidates in random order (by using a randomly re-ordered multiple CandidateMap-array)

About the levels...
1) Very Easy - Sudokus requiring only hidden singles
2) Easy - Sudokus also requiring naked singles
3) Medium - Sudokus also requiring box-line reductions and/or pointing pairs
4) Hard - Sudokus also requiring naked subsets
5) Very hard - Sudokus also requiring hidden subsets

Generated sudokus not answering to these levels are called "others".

Output files:
The following output file types are available:

1) MPQ Sudoku file type
Very Easy: Sudoku_Very_Easy.sds
Easy: Sudoku_Easy.sds
Medium: Sudoku_Medium.sds
Hard: Sudoku_Hard.sds
Very Hard: Sudoku_Very_Hard.sds
Others: Sudoku_Others.sds

Each file can hold multiple sudokus, format is built up this way:
There's no file-header, and each sudoku is saved in a 166 bytes long record. The first 81 bytes are reserved for the sudoku to be solved, and are saved in binary format. The following 81 bytes are holding the solution, also in binary format. The last 4 bytes of each sudoku record are reserved for keeping the best solving time for that sudoku, 2 bytes (in fact, an integer value) for the minutes, and another integer value for the seconds.
To import them with MPQ Sudoku, see the help file topic MPQ Sudoku – File Check and Import (only for advanced users)

2) Simple Sudoku file type
Very Easy: Very_Easy_0001.ss, Very_Easy_0002.ss, ...
Easy: Easy_0001.ss, Easy_0002.ss, ...
Medium: Medium_0001.ss, Medium_0002.ss, ...
Hard: Hard_0001.ss, Hard_0002.ss, ...
Very Hard: Very_Hard_0001.ss, Very_Hard_0002.ss, ...
Others: Others_0001.ss, Others_0002.ss, ...
Each file holds one sudoku, format is built up this way:
There's no file-header, and each sudoku is saved in text-format like this example:

Lunatic · Posted: Sun May 11, 2008 7:10 am Post subject:

May 11th 2008 - New update available - see above description
_________________
Marc
~~~<><~~~<><~~~<><~~~<><~~~

wapati · Posted: Tue May 13, 2008 7:07 pm Post subject:

I tried your generator and didn't mind it.

If you are still working on improving it I would suggest allowing a choice that cycles through the stored patterns and does one puzzle in each until stopped.

I print puzzles out and solve them and wouldn't much like them to all look the same. Smile

Next I'd add a few interesting methods, such as skyscraper, x-wing, xy wing and UR1.

Well done so far, it works and is quite capable at making newspaper type puzzles.

Lunatic · Posted: Thu May 15, 2008 9:06 pm Post subject:

Lunatic · Posted: Tue Oct 07, 2008 4:57 pm Post subject:

onthink · Posted: Sun Mar 29, 2009 12:39 pm Post subject:

It do need talents.