PlaySudoku.us
Hard · Puzzle #438
9
6
8
4
1
9
1
4
4
9
5
7
3
4
9
6
7
2
5
2
8
3
6
4
9
6
1
2
3
5
7
Donald Knuth's "Algorithm X" with dancing links solves exact cover problems — of which Sudoku is a special case.
Donald Knuth's "Algorithm X" with dancing links solves exact cover problems — of which Sudoku is a special case.
"Begin at once to live, and count each separate day as a separate life." — Seneca
"Begin at once to live, and count each separate day as a separate life." — Seneca