Su Doku Assistant

The Su Doku Assistant (SDA) is an easy-to-use Windows 7, Vista, XP, Me, 98, 95 based program for solving and creating 9x9 Su Doku puzzles.

Features of SDA include:

Extensive support for the manual solution of both symmetric and asymmetric Su Doku puzzles including:
Entry of pre-filled values via keyboard or mouse, or a combination of both.
Automatic checking of manually entered cell values to ensure conformance with the fundamental rule of Su Doku.
Identification of singletons – unfilled cells which can only take one value.
Identification of all the unfilled cells which can take a specific value.
Simultaneous display of potential candidate values for all unfilled cells.
Tool-tips on unfilled cells, each tool-tip listing the candidate values for that cell. Tool-tips are also provided for many SDA screen components.
Cell colouring, useful when utilising more advanced strategies such as Colouring, X-Wings, XY-Wings and Swordfish.
Backing up the state of a partially completed grid for subsequent restoration, if required.
An unlimited undo facility for removing manually entered values.
A "give me a hint" facility.
Powerful automatic solution of both symmetric and asymmetric Su Doku puzzles. SDA can solve any 9x9 Su Doku puzzle with a unique solution. Such puzzles range in complexity from level 1 (relatively easy) to level 6 (fiendishly difficult). By way of comparison, the puzzles published in most newspapers seldom exceed level 2 in difficulty.
Flexible new puzzle creation facilities. Both symmetric and asymmetric puzzles with a specified number of cells may be created, as may those with a specified level of difficulty in the range 1 (relatively easy) to 6 (fiendishly difficult).
Significant additional capabilities including:
Saving and reloading Su Doku puzzles in SDA .grd file format, whether partially or fully completed. Puzzles may also be saved in two popular plain text formats.
Loading Su Doku puzzles held in text files using various popular formats for facilitating puzzle entry and interchange.
Saving the history of the steps taken by SDA when solving a puzzle automatically and replaying these steps one by one.
The timing of the manual solution of puzzles. When an incompletely solved puzzle is saved, the time taken so far is also saved, in order that the correct time can be re-established if the puzzle is loaded again.
A facility to improve puzzles by removing redundant pre-fills.
Conversion of any asymmetric puzzle into a symmetric puzzle, or vice-versa.
Printing paper copies of puzzles for off-line solution.