This is a Windows command line .bat to solve a Sudoku puzzle. It
uses a brute force method (try all possible numbers) so it's very slow!
I wrote it just to see if it was possible to do in a batch script.
No external commands are used, only internal (SET, CALL, IF, FOR, etc).
There are no GOTO's in the script.
Enter just phsud to get a help message; or, supply the puzzle on the command
line, using . or 0 to indicate an empty square (spaces are ignored):
Missing trailing squares are assumed empty, so this is also valid:
If the argument exists as a file the unsolved puzzle is read from the file:
The puzzle is not checked; it is assumed to be valid. "Solved" simply
means a 1-9 could be legally placed in all empty squares.
The phsud.bat file (which can be download via a link beneath this listing):
Command line .bat to solve Sudoku puzzle
[page last modified 2022-04-07]
C>phsud ...63.9.. .....47.3 1....7.6. .875..2.. 4.2...3.5 ..6..287. .7.2....4 8.17..... ..9.81...
C>phsud 1.23
C>phsud board
@echo off& setlocal enabledelayedexpansion
rem Solves a sudoku puzzle -- see help message for more info.
set x=x%*& if "!x!"=="x" call :help& exit /b
if exist %1 set x=x& for /f "delims=" %%r in (%1) do set x=!x!%%r
set x=!x: =!& set x=!x:.=0!
set y=!x!& for /l %%c in (0,1,9) do set y=!y:%%c=!
if "!y!" neq "x" call :help :illegal board char(s): !y:~1!& exit /b
set y=000000000& set x=%x:~1%!y!!y!!y!!y!!y!!y!!y!!y!!y!
rem Below can create 100-200 env vars (depends on number of empty squares).
rem Using these helper env vars enables the core logic to run much faster.
for /l %%x in (0,1,8) do set x%%x=!x:~0,9!& set x=!x:~9!
set /a xx=100433766, xy=221554887, $=-1
for /l %%r in (0,1,8) do for /l %%c in (0,1,8) do set %%r%%c=!x%%r:~%%c,1!
set $$=1& for /l %%r in (8,-1,0) do for /l %%c in (8,-1,0) do (
if !%%r%%c!==0 if defined $$ (
set #%%r%%c=!$!^^!!xx:~%%r,1!!xx:~%%c,1!^^!^^!!xx:~%%r,1!!xy:~%%c,^
1!^^!^^!!xy:~%%r,1!!xx:~%%c,1!^^!^^!!xy:~%%r,1!!xy:~%%c,1!^^!
for /l %%i in (0,1,8) do (
if %%i neq %%c set #%%r%%c=!#%%r%%c!^^!%%r%%i^^!
if %%i neq %%r set #%%r%%c=!#%%r%%c!^^!%%i%%c^^!
)
set $=%%r%%c& set "$$="
for /f %%x in ("!#%%r%%c:~2!") do set x=%%x& for /l %%y in (1,1,9) do (
if "!x:%%y=!"=="!x!" set $$=!$$! %%y)
set #%%r%%c=!#%%r%%c!!$$!
)
)
if %$%==-1 call :help ~no empty board square(s) ***& exit /b
if not defined $$ call :help ~invalid board ***& exit /b
call :solve %$% || (call :help ~NO SOLUTION FOUND ***& exit /b)
call :dispb & exit /b
rem Solve all zeroes starting at %1= index of 1st zero currently in board.
rem Returns errorlevel 0 if solution found, 1 if no solution.
:solve
if %1==-1 exit /b 0
set $=!#%1:~2,80!
set +%1=%$%
for %%i in (!#%1:~82!) do if "!+%1:%%i=!"=="!+%1!" (
set %1=%%i& call :solve !#%1:~0,2! && exit /b 0)
set %1=0& exit /b 1
rem Display the 9x9 board
:dispb
(for /l %%r in (0,1,8) do (set "r="
for /l %%c in (0,1,8) do set r=!r!!%%r%%c!)& echo !r!)& exit /b
rem Display Error/Help. If args, output them error msg first.
:help
set x=%*& if defined x echo %~nx0: *** !x:~1!& if "!x:~0,1!"=="~" exit /b
echo.& echo %~nx0: 4/5/2022 version 1.1 http://paulhoule.com/phsud& echo.
echo Solves sudoku puzzle using brute force, so very slow^^!
echo Arg is puzzle: digits 1-9, 0 or . for empty square.
echo Arg may be a filename; if so, puzzle is read from there.
echo If puzzle is ^< 81 digits, trailing square(s) are assumed to be empty.
echo.& echo Examples:
echo %~n0 1023 -- 1,2,3 in top row indexes 0,2,3, all other squares 0
echo %~n0 brd -- board is read from file brd (brd must exist)
Click here to download phsud.bat
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