From: "M. Edward (Ed) Borasky" <znmeb@...>
Date: 2006-02-20T04:48:30+09:00
Subject: Re: Sodoku-Generator

From the R library package "sudoku":

generateSudoku            package:sudoku            R Documentation

Randomly Generate a Sudoku Puzzle Grid

Description:

     Creates a 9x9 Sudoku grid suitable for use by 'playSudoku'.

Usage:

       generateSudoku(Nblank=50, print.it=FALSE)

Arguments:

  Nblank: Number of cells to blank out

print.it: Logical.  If true, print result to screen.

Details:

     The basic algorithm is to start with a 'primordial' Sudoku grid,
     swap around some rows and columns, then blank out some cells.

Value:

     A matrix, representing a 9x9 Sudoku grid.

Author(s):

     Curt Seeliger <Seeliger.Curt@epamail.epa.gov>, Henrik Bengtsson
     <hb@maths.lth.se>, and David Brahm <brahm@alum.mit.edu>

References:

     <URL: http://sudoku.com/>

Examples:

     generateSudoku(print.it=TRUE)

Here's the function definition for those who understand R. I might make
pseudo-code from this if I have the time:

generateSudoku <- function(Nblank=50, print.it=FALSE) {
  z <- c(1:9,4:9,1:3,7:9,1:6,2:9,1,5:9,1:4,8:9,1:7,3:9,1:2,6:9,1:5,9,1:8)
  z <- matrix(sample(9)[z], 9,9)
  for (i in 1:5) z <- z[replicate(3, sample(3)) + 3*rep(sample(0:2),
each=3),
                        replicate(3, sample(3)) + 3*rep(sample(0:2),
each=3)]
  for (bi in seq(0,6,3)) for (bj in seq(0,6,3)) {
    idx <- data.matrix(expand.grid(bi + 1:3, bj + 1:3))
    z[idx[sample(1:9, Nblank%/%9), ]] <- 0
  }
  ## Depopulate (if we had a test for uniqueness, we'd put it here):
  while (sum(!z) < Nblank) z[matrix(sample(9,2), 1)] <- 0
  if (print.it) printSudoku(z)
  z
}



Meino Christian Cramer wrote:
> Hi,
>
>  with Google I found a Quiz about a Sodoku-solver, but I didn't find a
>  Sodoku generator. Also RAA and RubyForge did not list one.
>
>  Is there any out there ? May be one, which also generated a solution
>  for the generated Sodokus?
>
>  Kind regards,
>  mcc
>
>
>   

-- 
M. Edward (Ed) Borasky

http://linuxcapacityplanning.com