What is a Sudoku?
Sudoku is a mathematical game in which we have to fill a mesh of 81 cells with number from 1 to 9. The mesh is distributed in 9 rows and 9 columns. You must complete them with number from 1 to 9 making sure that on each row and on each column no number is repeated. Moreover, the board is divided into 9 squared blocks with 9 cells each one. On each block no number must be repeated too.