This is a simple sudoku solver that uses backtracking to solve the puzzle.
Initial board:
. . 7 | . 8 . | 4 . 2
. . 9 | . 5 . | . . .
. 8 . | . 7 4 | 5 . 9
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. . . | . . . | . 6 .
. . 1 | . . 5 | . 2 .
4 9 . | 8 . 7 | . 5 .
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7 3 4 | 5 1 6 | 2 9 8
. . 6 | . 2 . | . 4 .
. . . | . . . | . . .Solved board (in 0.07 seconds):
1 5 7 | 6 8 9 | 4 3 2
2 4 9 | 3 5 1 | 7 8 6
6 8 3 | 2 7 4 | 5 1 9
---------------------
3 7 5 | 1 9 2 | 8 6 4
8 6 1 | 4 3 5 | 9 2 7
4 9 2 | 8 6 7 | 1 5 3
---------------------
7 3 4 | 5 1 6 | 2 9 8
9 1 6 | 7 2 8 | 3 4 5
5 2 8 | 9 4 3 | 6 7 1