PlaySudoku.us
Hard · Puzzle #541
8
1
2
4
7
7
3
8
4
3
6
9
4
2
2
4
7
1
3
6
1
3
8
2
9
7
Donald Knuth's "dancing links" algorithm — published in 2000 — is one of the fastest ways to solve Sudoku by computer.
Donald Knuth's "dancing links" algorithm — published in 2000 — is one of the fastest ways to solve Sudoku by computer.
Always update pencil marks immediately after placing a digit — stale marks cause almost all solving errors.
Always update pencil marks immediately after placing a digit — stale marks cause almost all solving errors.