SUDOKU
Write a number from 1 to 9 into each empty square in the grid so that every number from 1 to 9 appears exactly once in each horizontal row, each vertical column, and each 3×3 block.
8
5
4
4
1
9
9
1
2
9
3
5
6
8
3
8
9
9
7
5
8
5
3
6
4
7
** Moderate