Sudoko program

This is my contribution to the infinite list of sudoku solvers. The syntax is

sudoku.pl [-<#>] [-r] [-s <symbols>] [-p <xx>] [<filename>]

Here

<#> is 2, 3, 4, or 5 giving the size of the problem (3 is default)
-r turns on randomness in initial permutations. This does not affect unique solutions but changes the order in which solutions are found. This can be useful for generating new sudokus if you don't want them to start out with 123456789 etc.
-s <symbols> sets the symbols used to the symbolstring which should be of the obvious size. Defaults are 1234, 123456789, 0123456789ABCDEF, and ABCDEFGHIJKLMNOPQRSTUVWXY for the different sizes.
<filename> is a file to read the puzzle from. The format should be obvious from the example below. The dots can be replaced by any non whitespace characters not in the symbol string. Whitespaces are ignored. If no filename is given the programs assumes an empty grid to start with.
if -p <xx> is given the program replaces xx percent of the symbols in the input filename by dots. In this case the effective new puzzle with more dots is printed at the start. This option can be used to create new puzzles: First run the program with -r and with no filename to generate a solution. Copy that to a file which in a second run using that as the input file now with -p adjusted to make the problem hard but with still a unique solution.

Here is a sample input file (taken from this week's sudoku in Die Zeit):

3.......4
.249.786.
..8...7..
.3.518.2.
.4.....5.
.5.429.7.
..6...2..
.836.294.
2.......7

Have fun!

Back to main page. Author: Robert C. Helling