Creational patterns

• Low binding factory pattern -> FileReaderFactory.kt
• Builder pattern -> SudokuModelBuilder.kt
• Singleton pattern (kind of) -> ViewManager.kt

Structural patterns

• Composite pattern -> SudokuModel.kt, SudokuGroup.kt, SudokuCell.kt

Behavioral patterns

• Visitor pattern -> SudokuModel.kt, SolveSudokuVisitor.kt
• State pattern (kind of) -> SudokuCell.kt, CellState.kt, SudokuController.kt