This is a simple solver for generalized Sudoku. In its strongest mode it uses a backtracking algorithm with the most constrained heuristic for variable (location) ordering and the least constraining heuristic for value ordering. On 'typical' 3x3 Sudoku puzzles it reaches a solution in 10s to 100s of milliseconds.
- C++11
All the source files are in the src directory, and require an include path at the project root directory. Compile them using your preferred method. For example using g++ go to src and run
g++ -std=c++11 -I.. -o sudoku main.cpp solver.cpp grid.cppcreating a sudoku console program. For fastest performance add the -O3 optimization option.
Where sudoku is the executable's name, the programs syntax follows
sudoku [-d SUB_ROWS SUB_COLS] [INPUT_FILE]The -d allows specifying custom dimensions for a Sudoku subgrid (default: 3x3). The INPUT_FILE is a file that contains grid definitions to solve. A grid definition is a list of of the grid's values, with 0 representing an empty square. The values can be delimited by any non-numeric characters. For example, the following three 3x3 grids are valid:
0 9 4 0 0 0 1 3 0
0 0 0 0 0 0 0 0 0
0 0 0 0 7 6 0 0 2
0 8 0 0 1 0 0 0 0
0 3 2 0 0 0 0 0 0
0 0 0 2 0 0 0 6 0
0 0 0 0 5 0 4 0 0
0 0 0 0 0 8 0 0 7
0 0 6 3 0 4 0 0 8
+-----+-----+-----+
|0 0 0|0 0 0|0 0 0|
|0 0 0|0 0 3|0 8 5|
|0 0 1|0 2 0|0 0 0|
+-----+-----+-----+
|0 0 0|5 0 7|0 0 0|
|0 0 4|0 0 0|1 0 0|
|0 9 0|0 0 0|0 0 0|
+-----+-----+-----+
|5 0 0|0 0 0|0 7 3|
|0 0 2|0 1 0|0 0 0|
|0 0 0|0 4 0|0 0 9|
+-----+-----+-----+
1.0.0.0.0.7.0.9.0.0.3.0.0.2.0.0.0.8.0.0.9.6.0.0.5.0.0
0.0.5.3.0.0.9.0.0.0.1.0.0.8
0.0.0.2.6.0.0.0.0.4.0.0.0.3
0.0.0.0.0.0.1
0.0.4.0.0.0.0
0.0.7.0
0.7.0.0
0.3.0.0
If the INPUT_FILE is unspecified then the program reads from stdin. When the algorithm has found a solution it outputs the solved grid and the time taken (as well as 'steps' in the algorithm -- number of search nodes traversed). When it has read all the grids in the input it also outputs the total time used for all puzzles. For the three grids above for example, the output would be something like
. 9 4 . . . 1 3 .
. . . . . . . . .
. . . . 7 6 . . 2
. 8 . . 1 . . . .
. 3 2 . . . . . .
. . . 2 . . . 6 .
. . . . 5 . 4 . .
. . . . . 8 . . 7
. . 6 3 . 4 . . 8
||
|| (1108 steps, 0.042s)
\/
7 9 4 5 8 2 1 3 6
2 6 8 9 3 1 7 4 5
3 1 5 4 7 6 9 8 2
6 8 9 7 1 5 3 2 4
4 3 2 8 6 9 5 7 1
1 5 7 2 4 3 8 6 9
8 2 1 6 5 7 4 9 3
9 4 3 1 2 8 6 5 7
5 7 6 3 9 4 2 1 8
----
. . . . . . . . .
. . . . . 3 . 8 5
. . 1 . 2 . . . .
. . . 5 . 7 . . .
. . 4 . . . 1 . .
. 9 . . . . . . .
5 . . . . . . 7 3
. . 2 . 1 . . . .
. . . . 4 . . . 9
||
|| (18115 steps, 0.573s)
\/
9 8 7 6 5 4 3 2 1
2 4 6 1 7 3 9 8 5
3 5 1 9 2 8 7 4 6
1 2 8 5 3 7 6 9 4
6 3 4 8 9 2 1 5 7
7 9 5 4 6 1 8 3 2
5 1 9 2 8 6 4 7 3
4 7 2 3 1 9 5 6 8
8 6 3 7 4 5 2 1 9
----
1 . . . . 7 . 9 .
. 3 . . 2 . . . 8
. . 9 6 . . 5 . .
. . 5 3 . . 9 . .
. 1 . . 8 . . . 2
6 . . . . 4 . . .
3 . . . . . . 1 .
. 4 . . . . . . 7
. . 7 . . . 3 . .
||
|| (196 steps, 0.008s)
\/
1 6 2 8 5 7 4 9 3
5 3 4 1 2 9 6 7 8
7 8 9 6 4 3 5 2 1
4 7 5 3 1 2 9 8 6
9 1 3 5 8 6 7 4 2
6 2 8 7 9 4 1 3 5
3 5 6 4 7 8 2 1 9
2 4 1 9 3 5 8 6 7
8 9 7 2 6 1 3 5 4
----
Solved 3 grids (0.623s)