Sudoku

This is a Sudoku app

How to start game

Please note that button New game is not working because Step 1 must be implemented
Main class: com.kaleyra.academy.sudoku.Sudoku.java

Step 1

Sudoku board is loaded from a file but the logic must be implemented inside file:

com.kaleyra.academy.sudoku.model.ModelDAO

Your code should be implemented at line 94 (see //TODO...)

This is the file containing a model for Sudoku board:

game1.sudoku

Please note that the first two lines inside files should be ignored. Here how to read the record:

P;0;2;8 <----- means P(redefined cell ) with value 8 placed inside cell with row 0 and column 2

Each predefined cell must be loaded inside the matrix at line 76:
```
int[][] predefinedCells =
                    new int[GameModel.ROWS][GameModel.COLS];
```
Step 2

Junit test DefaultValidationStrategyTest.java is broken and we have to implement logic in class com.kaleyra.academy.sudoku.model.strategy.validation.impl.DefaultValidationStrategy to let it pass.
Step 3 (bonus)

Find a way to switch game generation strategy with a config file
Step 4 (bonus)

A new requirement exists: Changing the game difficulty for the random generated model. This is now set by default set to MEDIUM in the class below.

SimpleGenerationStrategy.java

Note: For the sake of simplicity, game difficulty is supposed to change with the number of hidden cells inside sudoku board. For example, a game is considered easy when the number of predefined cells are is high.

Try to refactor this code to switch game difficulty from a property set inside file that can have three values: EASY, MEDIUM, HARD