This is a "plugin" for the Video Disk Recorder (VDR).

Written by:                  Thomas Günther <tom@toms-cafe.de>

Project's homepage:          http://toms-cafe.de/vdr/sudoku

Latest version available at: http://toms-cafe.de/vdr/sudoku

See the file COPYING for license information.


Description:
------------

'Sudoku' is a VDR plugin to generate and solve Number Place puzzles, so called
Sudokus.

A Sudoku puzzle consists of 9 x 9 cells subdivided into 9 regions with 3 x 3
cells. The rules are simple. There have to be the numbers from 1 to 9 in every
row, column and region. In the beginning some numbers are given. These cells are
painted with cyan background color. The aim of the puzzle is to find the missing
numbers. There is only one solution of a Sudoku puzzle.

The Sudoku puzzles are generated on-the-fly. The number of givens can be set in
the plugin's setup page down to a minimum of 26 givens. The generation of
puzzles with less than 26 givens takes too long. By default the cells with
givens are symmetrically ordered. But this can be disabled in the setup.

To solve difficult Sudoku puzzles some hints can be used. Incorrect cells are
red and cells with ambiguous numbers are magenta. These hints can be disabled in
the setup. With the green key a cell can be marked. A marked cell has green
background color. With the yellow key the cursor is moved to the next free cell
with minimal possible numbers. The red key set the next possible number for the
current cell.

Each time the plugin is started from the main menu the same puzzle is shown. A
new puzzle is only generated on VDR startup or if it has been requested by
pressing the blue key. This key has two functions. If no numbers are set a new
puzzle is generated. Otherwise all numbers are reset so that only the givens are
shown.


Setup:
------

- Givens count            Givens count of the generated puzzles (26-81).
                          Default is 36.
- Symmetric givens        Cells with givens are symmetrically ordered (yes/no).
                          Default is yes.
- Mark errors             Incorrect cells are marked with red color (yes/no).
                          Default is yes.
- Mark ambiguous numbers  Cells with ambiguous numbers are marked with magenta
                          color (yes/no).
                          Default is yes.
- Transparency (%)        Set the transparency of the menu (0-100).
                          Default is 50.


Keys:
-----

- Left/Right/Up/Down      Move the cursor in the puzzle.
- 1-9                     Set the number in the current cell.
- 0                       Remove the number from the current cell.
- Green                   Mark/unmark the current cell.
- Yellow                  Move the cursor to the next free cell with minimal
                          possible numbers.
- Red                     Set the next possible number for the current cell -
                          reset the number if greater numbers are not possible.
- Blue                    Reset the puzzle (if some numbers set).
                          Start a new puzzle (if no numbers set).
- Back                    Quit the plugin.


Cell colors:
------------

- Cyan                    Givens
- Green                   Marked cells
- Red                     Incorrect cells
- Magenta                 Ambiguous numbers