The program gives a sorted list of all (well, at most 6,670,903,752,021,072,936,960) solutions of an input Sudoku grid. It supports suspending a computation after writing out state to a text file. It can resume the same computation (even on some other computer) after reading in the generated text file.
It can be used in mathematical exploration of properties of Sudoku. or as a very ( so I hope, and you can't sue me, and please tell me if you benchmark it ) fast Sudoku solver/generator.
$ make
$ ./sud 800000000003600000070090200050007000000045700000100030001000068008500010090000400
INPUT Sudoku grid (a 9x9 matrix) is given as first command line argument.
Its chars represent Sudoku cells, in row order. All chars except
'1'-'9' are interpreted as empty cells. If the argument string is
smaller than 81 chars the rest of the cells are assumed to be empty.
The program lists all Sudokus that satisfy the constraints expressed in the INPUT Sudoku grid, in form of 81 character strings, one on each line.
If INPUT string specifies that all cells are empty (no constraint), it will list all Sudoku grids that exist.
"123456789" is the default first argument if none is given.
If too many Sudokus satisfy INPUT constraints, then listing of all solutions may take a lot of time. For this reason, a method to suspend and resume the calculation is supported. A program can be suspended by pressing Ctrl+C.
The keyboard interrupt signal (Ctrl+C) terminates the program after
dumping its state to a text file named dump in current directory.
Later, if the program is run without arguments and a file named
dump is present in the current directory, it tries to load state
from it and resume a previously suspended listing.
The program shows number of Sudokus listed in each session on stderr, i.e. the number of solutions found from resume/start to suspension/termination of computation. You can keep track of them, and add them up when required, to count all listed values in whole computation. The counter will not overflow for any input string.
The source code can be compiled on any platform that has an ANSI C compiler with standard C library implemented.
Generated dump files may have to converted to properly encoded chars
on different platform.
Some (very old but working) categorized source code is given in extra/
directory. extra/tut.c is a tutorial, it tries to explain the algorithm.
This has took 4 years of my part time attention. born out of my jealousy about a friend solving newspaper Sudokus faster than me. :D
Please point out if it does not work as exhibited. I will correct it.
I am in search of a computer with enough resources to undertake the task of histogramming all Sudokus.
or should i make a distributed system!? but terabytes of data transfer?! anyway.
webster15july@gmail.com Fri Feb 28 00:38:23 IST 2014 pk