7
4
7
2
5
2
6
9
3
1
8
5
7
9
5
4
3
8
7
2
1
1
4
6
3
5
7
9
6
8
3
Check columns before rows — columns are often harder to complete and contain more useful constraints.
Check columns before rows — columns are often harder to complete and contain more useful constraints.
Some hospitals use Sudoku as a cognitive exercise for patients recovering from strokes or brain injuries.
Some hospitals use Sudoku as a cognitive exercise for patients recovering from strokes or brain injuries.