How to Generate a -complete- sudoku board? algorithm error

Question

I\'m trying to generate a complete (ie, each cell filled with a number) Sudoku-like board. It\'s for something else that has nothing to do with sudokus, so I am not interest

Answer 1

Start out with a solved Sudoko like this:

ABC DEF GHI
329 657 841 A
745 831 296 B
618 249 375 C

193 468 527 D
276 195 483 E
854 372 619 F

432 716 958 G 
587 923 164 H 
961 584 732 I

And then permutate it by switching columns and switching rows. If you only switch within the following groups ABC, DEF, GHI, the Sudoku is still solved.

A permutated version (switching columns):

BCA DFE IGH   
293 675 184 A 
457 813 629 B 
186 294 537 C 

931 486 752 D 
762 159 348 E 
548 327 961 F 

324 761 895 G 
875 932 416 H 
619 548 273 I 

And after some more permutation (switching rows):

BCA DFE IGH   
293 675 184 A 
186 294 537 C 
457 813 629 B 

931 486 752 D 
548 327 961 F 
762 159 348 E 

875 932 416 H 
619 548 273 I 
324 761 895 G