Sudoku Solver

Two modes are designed for the app: play mode and solver mode.
- In play mode, the user can get a random sudoku grid with 3 levels. The score will be calculated according to the level, the time and the number of successful boxes.
- In solver mode, the user can enter a missing sudoku grid to solve

User guide:
HOW TO PLAY ⍰
➤ How do I enter numbers into a cell?
- Tap a cell to select it
- Tap the numbers under the grid to apply
- Apply a second time to delete it

➤ 🔀 Solver Mode:
- Change the interface in Solver mode
- Use it to automatically solve a given grid

➤ 🔀 Play Mode:
- Change the interface in Play mode
- Use it to solve a given grid yourself

➤ 🗑 Clean:
- Clean the selected cell

➤ 🎨 Highlight:
- Use it to memorize a cell
- Tap to highlight the selected cell
- Apply a second time to remove the highlight

➤ 💡 Hint:
- Show index number in selected cell

➤ 🔁 New Grid:
- In Solver mode: Clean all cells
- In Play mode: Create a new grid with the selected level

➤ Level: 🏆: difficult; 🏅: medium; 💛: easy

➤ 🏁 Check: (play mode only)
- Tap to check if your solution is correct
- Correct cells are displayed in green
- Incorrect cells are displayed in red

➤ 💪 Solver: (solver mode only)
- Touch to solve the given grid