/// <summary>
/// This function takes in a sudoku and checks if it's valid and returns a boolean based on the result
/// </summary>
/// <param name="sudoku"></param>
/// <returns>true if the sudoku is valid</returns>
private bool IsValidGrid(int[,] sudoku)
{
if (!CheckGrid.Check(sudoku))
{
MessageBox.Show("De sudoku is niet oplosbaar");
return(false);
}
return(true);
}
/// <summary>
/// This function takes in the sudoku as a parameter
/// It will search for the first unfilled spot and fills it
/// Then it will check if the solution is still valid. If so perform a recursive call
/// Else try another number
/// </summary>
/// <param name="_sudoku"></param>
/// <returns>A boolean based on the fact if the sudoku is solvable</returns>
public bool Solve(int[,] _sudoku)
{
// Make a clone of the array and use it in this function
int[,] sudoku = new int[size, size];
sudoku = (int[, ])_sudoku.Clone();
// Initialize a few variables
int row, column = 0;
int number = 0;
// Find the first empty box in the sudoku
for (row = 0; number != -1 && row < size; row++)
{
for (column = 0; number != -1 && column < size; column++)
{
number = sudoku[row, column];
}
}
column--;
row--;
int i = 1;
bool solved = false;
// Try to solve the sudoku, if it tries to fill in a number greater than the size or it is already solved it stops.
while (i < size + 1 && !solved)
{
sudoku[row, column] = i;
if (CheckGrid.Check(sudoku))
{
if (CheckGrid.IsSolved(sudoku))
{
solution = sudoku;
return(true);
}
else
{
solved = Solve(sudoku);
}
}
i++;
}
// Return if the sudoku is solved or not
return(solved);
}