Sudoku is a mathematical game originated from Switzerland in the 18th century. It is a logic game using paper and pen. Players need to according to 9 × 9. For the known numbers on the disk, infer the numbers of all remaining spaces, and ensure that the numbers in each row, column and thick line Palace (3 * 3) contain 1-9 without repetition.

Classic and fun.
Suitable for killing time when bored.