Sudoku is a logical game that uses paper and pen to calculate. Players need to infer the numbers of all remaining spaces according to the known numbers on the 9×9 disk, and ensure that the numbers in each row, column and thick line palace contain 1-9 without repetition.

Every qualified Sudoku puzzle has a unique answer, and the reasoning method is based on it. Any problem with no solution or multiple solutions is unqualified.

Excerpt from Baidu Encyclopedia

And satisfy that every line, every column and every number in the thick line palace contains 1-9, which is not repeated.

Repeat the third line