improve Sudoku by using interface Basic
add method getMembersByGroup
testing result as follows,
 --- Sudoku 9x9 ---
 1 2 3 4 5 6 7 8 9
 . . . . . . . . .
 . . . . . . . . .
 . . . . . . . . .
 . . . . . . . . .
 . . . . . . . . .
 . . . . . . . . .
 . . . . . . . . .
 . . . . . . . . .
known cells count: 9

 --- Sudoku 9x9 ---
 1 2 3 4 5 6 7 8 9
 1 2 3 4 5 6 7 8 9
 . . . . . . . . .
 . . . . . . . . .
 . . . . . . . . .
 . . . . . . . . .
 . . . . . . . . .
 . . . . . . . . .
 . . . . . . . . .
known cells count: 18

 --- Sudoku 9x9 ---
 1 2 3 4 5 6 7 8 9
 1 2 3 4 5 6 7 8 9
 1 2 3 4 5 6 7 8 9
 . . . . . . . . .
 . . . . . . . . .
 . . . . . . . . .
 . . . . . . . . .
 . . . . . . . . .
 . . . . . . . . .
known cells count: 27

 --- Sudoku 9x9 ---
 1 2 3 4 5 6 7 8 9
 1 2 3 4 5 6 7 8 9
 1 2 3 4 5 6 7 8 9
 1 2 3 4 5 6 7 8 9
 . . . . . . . . .
 . . . . . . . . .
 . . . . . . . . .
 . . . . . . . . .
 . . . . . . . . .
known cells count: 36

 --- Sudoku 9x9 ---
 1 2 3 4 5 6 7 8 9
 1 2 3 4 5 6 7 8 9
 1 2 3 4 5 6 7 8 9
 1 2 3 4 5 6 7 8 9
 1 2 3 4 5 6 7 8 9
 . . . . . . . . .
 . . . . . . . . .
 . . . . . . . . .
 . . . . . . . . .
known cells count: 45

 --- Sudoku 9x9 ---
 1 2 3 4 5 6 7 8 9
 1 2 3 4 5 6 7 8 9
 1 2 3 4 5 6 7 8 9
 1 2 3 4 5 6 7 8 9
 1 2 3 4 5 6 7 8 9
 1 2 3 4 5 6 7 8 9
 . . . . . . . . .
 . . . . . . . . .
 . . . . . . . . .
known cells count: 54

 --- Sudoku 9x9 ---
 1 2 3 4 5 6 7 8 9
 1 2 3 4 5 6 7 8 9
 1 2 3 4 5 6 7 8 9
 1 2 3 4 5 6 7 8 9
 1 2 3 4 5 6 7 8 9
 1 2 3 4 5 6 7 8 9
 1 2 3 4 5 6 7 8 9
 . . . . . . . . .
 . . . . . . . . .
known cells count: 63

 --- Sudoku 9x9 ---
 1 2 3 4 5 6 7 8 9
 1 2 3 4 5 6 7 8 9
 1 2 3 4 5 6 7 8 9
 1 2 3 4 5 6 7 8 9
 1 2 3 4 5 6 7 8 9
 1 2 3 4 5 6 7 8 9
 1 2 3 4 5 6 7 8 9
 1 2 3 4 5 6 7 8 9
 . . . . . . . . .
known cells count: 72

 --- Sudoku 9x9 ---
 1 2 3 4 5 6 7 8 9
 1 2 3 4 5 6 7 8 9
 1 2 3 4 5 6 7 8 9
 1 2 3 4 5 6 7 8 9
 1 2 3 4 5 6 7 8 9
 1 2 3 4 5 6 7 8 9
 1 2 3 4 5 6 7 8 9
 1 2 3 4 5 6 7 8 9
 1 2 3 4 5 6 7 8 9
known cells count: 81

 --- Sudoku 9x9 ---
 1 2 3 4 5 6 7 8 9
 2 2 3 4 5 6 7 8 9
 3 2 3 4 5 6 7 8 9
 4 2 3 4 5 6 7 8 9
 5 2 3 4 5 6 7 8 9
 6 2 3 4 5 6 7 8 9
 7 2 3 4 5 6 7 8 9
 8 2 3 4 5 6 7 8 9
 9 2 3 4 5 6 7 8 9
known cells count: 81

 --- Sudoku 9x9 ---
 1 1 3 4 5 6 7 8 9
 2 2 3 4 5 6 7 8 9
 3 3 3 4 5 6 7 8 9
 4 4 3 4 5 6 7 8 9
 5 5 3 4 5 6 7 8 9
 6 6 3 4 5 6 7 8 9
 7 7 3 4 5 6 7 8 9
 8 8 3 4 5 6 7 8 9
 9 9 3 4 5 6 7 8 9
known cells count: 81

 --- Sudoku 9x9 ---
 1 1 1 4 5 6 7 8 9
 2 2 2 4 5 6 7 8 9
 3 3 3 4 5 6 7 8 9
 4 4 4 4 5 6 7 8 9
 5 5 5 4 5 6 7 8 9
 6 6 6 4 5 6 7 8 9
 7 7 7 4 5 6 7 8 9
 8 8 8 4 5 6 7 8 9
 9 9 9 4 5 6 7 8 9
known cells count: 81

 --- Sudoku 9x9 ---
 1 1 1 1 5 6 7 8 9
 2 2 2 2 5 6 7 8 9
 3 3 3 3 5 6 7 8 9
 4 4 4 4 5 6 7 8 9
 5 5 5 5 5 6 7 8 9
 6 6 6 6 5 6 7 8 9
 7 7 7 7 5 6 7 8 9
 8 8 8 8 5 6 7 8 9
 9 9 9 9 5 6 7 8 9
known cells count: 81

 --- Sudoku 9x9 ---
 1 1 1 1 1 6 7 8 9
 2 2 2 2 2 6 7 8 9
 3 3 3 3 3 6 7 8 9
 4 4 4 4 4 6 7 8 9
 5 5 5 5 5 6 7 8 9
 6 6 6 6 6 6 7 8 9
 7 7 7 7 7 6 7 8 9
 8 8 8 8 8 6 7 8 9
 9 9 9 9 9 6 7 8 9
known cells count: 81

 --- Sudoku 9x9 ---
 1 1 1 1 1 1 7 8 9
 2 2 2 2 2 2 7 8 9
 3 3 3 3 3 3 7 8 9
 4 4 4 4 4 4 7 8 9
 5 5 5 5 5 5 7 8 9
 6 6 6 6 6 6 7 8 9
 7 7 7 7 7 7 7 8 9
 8 8 8 8 8 8 7 8 9
 9 9 9 9 9 9 7 8 9
known cells count: 81

 --- Sudoku 9x9 ---
 1 1 1 1 1 1 1 8 9
 2 2 2 2 2 2 2 8 9
 3 3 3 3 3 3 3 8 9
 4 4 4 4 4 4 4 8 9
 5 5 5 5 5 5 5 8 9
 6 6 6 6 6 6 6 8 9
 7 7 7 7 7 7 7 8 9
 8 8 8 8 8 8 8 8 9
 9 9 9 9 9 9 9 8 9
known cells count: 81

 --- Sudoku 9x9 ---
 1 1 1 1 1 1 1 1 9
 2 2 2 2 2 2 2 2 9
 3 3 3 3 3 3 3 3 9
 4 4 4 4 4 4 4 4 9
 5 5 5 5 5 5 5 5 9
 6 6 6 6 6 6 6 6 9
 7 7 7 7 7 7 7 7 9
 8 8 8 8 8 8 8 8 9
 9 9 9 9 9 9 9 9 9
known cells count: 81

 --- Sudoku 9x9 ---
 1 1 1 1 1 1 1 1 1
 2 2 2 2 2 2 2 2 2
 3 3 3 3 3 3 3 3 3
 4 4 4 4 4 4 4 4 4
 5 5 5 5 5 5 5 5 5
 6 6 6 6 6 6 6 6 6
 7 7 7 7 7 7 7 7 7
 8 8 8 8 8 8 8 8 8
 9 9 9 9 9 9 9 9 9
known cells count: 81

 --- Sudoku 9x9 ---
 1 2 3 1 1 1 1 1 1
 4 5 6 2 2 2 2 2 2
 7 8 9 3 3 3 3 3 3
 4 4 4 4 4 4 4 4 4
 5 5 5 5 5 5 5 5 5
 6 6 6 6 6 6 6 6 6
 7 7 7 7 7 7 7 7 7
 8 8 8 8 8 8 8 8 8
 9 9 9 9 9 9 9 9 9
known cells count: 81

 --- Sudoku 9x9 ---
 1 2 3 1 2 3 1 1 1
 4 5 6 4 5 6 2 2 2
 7 8 9 7 8 9 3 3 3
 4 4 4 4 4 4 4 4 4
 5 5 5 5 5 5 5 5 5
 6 6 6 6 6 6 6 6 6
 7 7 7 7 7 7 7 7 7
 8 8 8 8 8 8 8 8 8
 9 9 9 9 9 9 9 9 9
known cells count: 81

 --- Sudoku 9x9 ---
 1 2 3 1 2 3 1 2 3
 4 5 6 4 5 6 4 5 6
 7 8 9 7 8 9 7 8 9
 4 4 4 4 4 4 4 4 4
 5 5 5 5 5 5 5 5 5
 6 6 6 6 6 6 6 6 6
 7 7 7 7 7 7 7 7 7
 8 8 8 8 8 8 8 8 8
 9 9 9 9 9 9 9 9 9
known cells count: 81

 --- Sudoku 9x9 ---
 1 2 3 1 2 3 1 2 3
 4 5 6 4 5 6 4 5 6
 7 8 9 7 8 9 7 8 9
 1 2 3 4 4 4 4 4 4
 4 5 6 5 5 5 5 5 5
 7 8 9 6 6 6 6 6 6
 7 7 7 7 7 7 7 7 7
 8 8 8 8 8 8 8 8 8
 9 9 9 9 9 9 9 9 9
known cells count: 81

 --- Sudoku 9x9 ---
 1 2 3 1 2 3 1 2 3
 4 5 6 4 5 6 4 5 6
 7 8 9 7 8 9 7 8 9
 1 2 3 1 2 3 4 4 4
 4 5 6 4 5 6 5 5 5
 7 8 9 7 8 9 6 6 6
 7 7 7 7 7 7 7 7 7
 8 8 8 8 8 8 8 8 8
 9 9 9 9 9 9 9 9 9
known cells count: 81

 --- Sudoku 9x9 ---
 1 2 3 1 2 3 1 2 3
 4 5 6 4 5 6 4 5 6
 7 8 9 7 8 9 7 8 9
 1 2 3 1 2 3 1 2 3
 4 5 6 4 5 6 4 5 6
 7 8 9 7 8 9 7 8 9
 7 7 7 7 7 7 7 7 7
 8 8 8 8 8 8 8 8 8
 9 9 9 9 9 9 9 9 9
known cells count: 81

 --- Sudoku 9x9 ---
 1 2 3 1 2 3 1 2 3
 4 5 6 4 5 6 4 5 6
 7 8 9 7 8 9 7 8 9
 1 2 3 1 2 3 1 2 3
 4 5 6 4 5 6 4 5 6
 7 8 9 7 8 9 7 8 9
 1 2 3 7 7 7 7 7 7
 4 5 6 8 8 8 8 8 8
 7 8 9 9 9 9 9 9 9
known cells count: 81

 --- Sudoku 9x9 ---
 1 2 3 1 2 3 1 2 3
 4 5 6 4 5 6 4 5 6
 7 8 9 7 8 9 7 8 9
 1 2 3 1 2 3 1 2 3
 4 5 6 4 5 6 4 5 6
 7 8 9 7 8 9 7 8 9
 1 2 3 1 2 3 7 7 7
 4 5 6 4 5 6 8 8 8
 7 8 9 7 8 9 9 9 9
known cells count: 81

 --- Sudoku 9x9 ---
 1 2 3 1 2 3 1 2 3
 4 5 6 4 5 6 4 5 6
 7 8 9 7 8 9 7 8 9
 1 2 3 1 2 3 1 2 3
 4 5 6 4 5 6 4 5 6
 7 8 9 7 8 9 7 8 9
 1 2 3 1 2 3 1 2 3
 4 5 6 4 5 6 4 5 6
 7 8 9 7 8 9 7 8 9
known cells count: 81