Welcome to SudokuSolver, a set of C++ classes which implements support for the
classic 9*9 Sudoku puzzle as well as a simple MFC Dialog based app which generates
and solves Sudoku puzzles.
- Provides a simple C++ Header only module and class to represent a Sudoku
grid. The class in this header is called CSudokuGrid and provides most of the
- The sample app provides a simple VC 2017 dialog based Sudoku puzzle generator
and solver. If you click the "Generate" button in the sample app,
it will generate a solvable puzzle with the specified number of cells left empty
(as taken from the empty cells edit box). The algorithm to generate a puzzle
is based on the information from
- The solving code demonstrates how to integrate MFC multithreading into a
algorithm in a manner such that it is cancellable and provides UI feedback while
running without the need to provide a blocking modal dialog UI. The logic for
this is spread across the methods of the CSudokuSolverDlg class. The solving
code is based on a subset of the information from
- As the solving code runs it will set the background colour of the cell which
it is operating on in red and indicate the depth of the algorithm using ""
in the cell. The code to do this is executing from a worker thread but to update
the UI the main thread must do the actual work. To avoid overloading the main
thread with update requests, the worker thread implements logic to only update
the UI every 100 ms. To review this code, please take a look at the CSudokuSolverDlg::Solve
- When the solving code finds a solution it will set the background colour
of any updated cells to green.
- The background colouring of the edit boxes is done with a very simple CColorEdit
MFC class which is derived from the standard CEdit control class. This class
demonstrates how to implement background colors in an edit box using MFC using
the standard WM_CTLCOLOR message handling mechanism.
- Please note that as the solving algorithm is currently implemented it will
not guarantee that there is only one solution to the provided puzzle and instead
will just pick the first solution found.
- The code demonstrates the various pieces of code required to implement MFC
multithreading for a long running algorithm while keeping the UI responsive.
- Construction and clean destruction of worker threads
- Correct use of Thread priorities
- Using asynchronous UI notification using Windows messaging using PostMessage
- Implementing a cancellable thread using WaitForSingleObject and MFC
- Status reporting from the worker thread using windows message, critical
sections and MFC message maps
- Implementing worker threads in MFC using non static class methods via
the LPVOID parameter to the AfxBeginThread API
- Implementing worker threads in MFC which are awaitable from their creation
- Avoiding choking the UI thread with too many notifications from the
- All told the multithreading logic is spread across custom WM_* messages,
the MFC message map, the UI thread, class member variables, static and non static
methods. I plan to re-implement the solving algorithm in a future version of
the code using the
(Parallel Patterns Library) to be able to compare the custom MFC implementation
currently in the code with the hopefully cleaner implementation using PPL and
lambdas. This should also allow me to tweak the algorithm to take advantage
of today's multi-core processors with relative ease without the need to write
a custom thread pool implementation.
The enclosed zip file contains the SudokuSolver
source code and a simple VC 2017 MFC dialog based application which demonstrates
most of the classes functionality.
- You are allowed to include the source code in any product (commercial, shareware,
freeware or otherwise) when your product is released in binary form.
- You are allowed to modify the source code in any way you want except you
cannot modify the copyright details at the top of each module.
- If you want to distribute source code with your application, then you are
only allowed to distribute versions released by the author. This is to maintain
a single distribution point for the source code.
V1.04 (30 December 2018)
- Updated copyright details.
- Fixed a number of C++ core guidelines compiler warnings. These changes
mean that the code will now only compile on VC 2017 or later.
V1.03 (17 May 2016)
- Updated copyright details.
- Updated the sample app to compile cleanly using /analyze
- Updated the code to compile cleanly on VC 2015
V1.02 (9 November 2013)
- Fixed a bug in the Hint algorithm. In v1.01 it would put values in cells
which were the first possible value for a cell which had multiple choices. Now
the code determines if it has run out of definite cells to fill as you repeatedly
hit the "Hint" button and prompts the user to allow the program to
solve the puzzle so that it can provide the next hint.
- General cleanup to the code in SudokuSolverDlg.cpp
V1.01 (5 November 2013)
- App now includes support for a Hint feature where it will fill in the next
appropriate cell but not do a complete solve of the puzzle.
V1.0 (3 November 2013)