PlaySudoku.us
Hard · Puzzle #997
9
3
5
5
9
8
1
6
8
5
7
4
1
8
4
7
8
3
1
7
8
9
7
5
3
4
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