PlaySudoku.us
Expert · Puzzle #161
5
6
1
4
3
9
4
2
8
7
9
5
2
4
9
2
7
2
1
7
8
8
4
1
"The secret of getting ahead is getting started." — Mark Twain
"The secret of getting ahead is getting started." — Mark Twain
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.