Usage Instructions

for Sudoku Solver, version 4.4

Automatic solving

Check the box to solve automatically, while you type. Cells are solved and candidates are eliminated as far as possible using the methods chosen. With complete elimination only candidates remain that will leed to a valid solution. Because the complete elimination is done in a separate thread, you may type a false candidate if you're fast, though.
With manual solving, only basic and advanced elimination is done. No cells are solved.

Elimination: basic, advanced, complete

See method descripton.

Candidates: squares, small digits

The graphics always show candidates in each cell. If "squares" is chosen, the position of the square within the cell decides which number it represents. If "small digits" is chosen, candidates are listed in order and centered within the cell. In the next version I might allow candidate digits to be positioned according to thier value, as in many other sudoku solvers, but that makes them very small and thus difficult to see.
When printing on paper no squares are shown, but the small digits are printed as on screen.

Highlighting candidates

You can highlight the candidate n (in yellow) by pressing <SHIFT> H + n. For instance H6 will mark all 6s. Pressing <SHIFT> H again will return the program to normal mode.

Solve button

Pressing the solve button will do solving once, with the methods available and the with the cell values and candidates showing. First, cells are solved using the tree basic methods, and the corresponding candidates are eliminated in the same box, row and column. Second, advanced methods are used one after the other to eliminate candidates, still using the board as it looked before the solving started. Third, complete elimination will be done in four steps. The first step is always done (if "complete" is checked), and the next is done only if the previous step didn't give any eliminations. The steps are (1a) one step testing for bi-location and bi-value candidates (1b) one step testing for other candidates (2a) multiple step testing for bi-location and bi-value candidates (2b) multiple step testing for other candidates. For a more detailed description of the elimination techniques, see the method descripton.

Clear button

If automatic is chosen, pressing "clear" once will erase all cells. With manual solving, pressing "clear" once will erase all solved cells. If advanced or complete elimination is chosen, the advanced methods are then used once, as if the givens had been typed again. Pressing clear again will erase everything. The output window is also cleared, but all printouts can still be seen in the java system window.

Save button

You can save the text version of the board to a file. The text is appended to the end of the file, so if you get a warning about replacing an existing file, just ignore it. The text is the same as with "print" without candidates, and is also copied to the text window.

Load button

To load a new board without having to type all the digits, copy to the text window at the bottom or the main text window. If the bottom window is empty (or contains no valid characters) the main output window is used instead. Valid characters are "123456789._0", where "._0" represent empty cells. All other characters, like "+", "-" and space, are ignored. So your input might look like this:
________1+__5______+_____7__3+_________+1____2___+____5_84_+__4_6____+_56_____7+_____1_32
000000001005000000000007003000000000100002000000050840004060000056000007000001032

Permute button

The current board is changed to an equivalent random permutation using 6 steps.
(1) Transponate. Interchanging rows and columns.
(2a) Box row permutation. There are three box rows. For instance box row 2 consists of boxes 4/5/6 and rows 4/5/6.
(2b) Row permutation within box rows. For instance rows 7/8/9 in box row 3 can be permuted in 3! = 6 ways (7/8/9, 7/9/8, 8/7/9, 8/9/7, 9/7/8, 9/8/7).
(3a) Box column permutation. There are three box columns. For instance box column 1 consists of boxes 1/4/7 and columns 1/2/3.
(3b) Column permutation within box columns.
(4) Permutation of the 9 digits.
The maximum number of different permutations is thus 2 * 6 * 63 * 6 * 63 * 9! = 3359232 * 362880 = 1,218,998,108,160. Most valid boards do in fact give this many possibilities, but a few (much less than 1 percent) like the following have special symmetries:
+-------+-------+-------+
| 1 2 3 | 4 5 6 | 7 8 9 | 
| 4 5 6 | 7 8 9 | 1 2 3 | 
| 7 8 9 | 1 2 3 | 4 5 6 | 
+-------+-------+-------+
| 2 3 4 | 5 6 7 | 8 9 1 | 
| 5 6 7 | 8 9 1 | 2 3 4 | 
| 8 9 1 | 2 3 4 | 5 6 7 | 
+-------+-------+-------+
| 3 4 5 | 6 7 8 | 9 1 2 | 
| 6 7 8 | 9 1 2 | 3 4 5 | 
| 9 1 2 | 3 4 5 | 6 7 8 | 
+-------+-------+-------+

Print button

Printing on paper should look exacly the same as on screen, except for when "squares" is chosen showing candidates. Then usolved cells are left empty. The board is 80 mm (3.15 inches) wide on my printer. I have set the printing positions to fit 6 boards on an A4 paper, and if you use another paper size you may want to change the settings in the source code. Printing starts in the upper left corner (position 1), and is moved one step for every "print" or "print later". To clear the memory, press "print" and then cancel.
The board is also copied to the text window and Java system window, using the syntax shown below. I have chosen to indent given and solved cell values, so they look different from cells with only one candidate.
If your browser doesn't allow an applet to print, I recommend running in application mode.

"Squares"

........1..5...........7..3.........1....2.......5.84...4.6.....56.....7.....1.32
+-------+-------+-------+
| . . . | . . . | . . 1 | 
| . . 5 | . . . | . . . | 
| . . . | . . 7 | . . 3 | 
+-------+-------+-------+
| . . . | . . . | . . . | 
| 1 . . | . . 2 | . . . | 
| . . . | . 5 . | 8 4 . | 
+-------+-------+-------+
| . . 4 | . 6 . | . . . | 
| . 5 6 | . . . | . . 7 | 
| . . . | . . 1 | . 3 2 | 
+-------+-------+-------+

"Small digits"

...........2.......3...19.............82..7...5....49......5..6....13.....7....28
+----------------------+--------------------------+-----------------------+
| 1456789 146789 14569 | 3456789  23456789 246789 | 123568 1345678 123457 |
| 1456789 146789  2    | 3456789  3456789  46789  | 13568  1345678 13457  |
| 45678    3     456   | 45678    245678    1     |  9     45678   2457   |
+----------------------+--------------------------+-----------------------+
| 1234679 124679 13469 | 13456789 3456789  46789  | 123568 13568   1235   |
| 13469   1469    8    |  2       34569    469    |  7     1356    135    |
| 12367    5     136   | 13678    3678     678    |  4      9      123    |
+----------------------+--------------------------+-----------------------+
| 123489  12489  1349  | 4789     24789     5     | 13     1347     6     |
| 245689  24689  4569  | 46789     1        3     | 5      457     4579   |
| 134569  1469    7    | 469      469      469    | 135     2       8     |
+----------------------+--------------------------+-----------------------+

Last modifed 2008-11-20