cgSudoku
Sudoku engine for .NET 4.0 and up
...An UndoManager class is provided for automatic undo/redo support, and basic file saving and loading to and from an XML format is implemented as well.
Also includes a custom control to drop on forms to take care of the display and basic key handling, and a sample WinForms application to demonstrate the basic functionality of the library and control.
Source is currently being developed in Visual Studio 2015, although it does not rely heavily on C# 6.0 features and could probably be converted to an earlier version with little trouble.
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