Add a new method named rule3 to the Sudoku class of the case study in this chapter. This method implements the following strategy: ■ Consider each column. ■ Consider each number missing from the...

Add a new method named rule3 to the Sudoku class of the case study in this chapter. This

method implements the following strategy:

■ Consider each column.

■ Consider each number missing from the column.

■ If the number can go in only one place within the column, put it there.

■ Repeat until there are no further changes

You should run the new method if the rule1 method and rule2 method fail to eliminate all the zeros from the board