// Creation for each cell list of possible values.
public static void CreatePossible(this Cell[,] matrix)
{
for (int yi = 0; yi < 9; yi++)
{
for (int xi = 0; xi < 9; xi++)
{
if (!matrix[xi, yi].IsKnown)
{
for (int num = 1; num <= 9; num++)
{
if (matrix.IsPossible(xi, yi, num))
{
if (matrix[xi, yi].Possibles == null)
{
matrix[xi, yi].Possibles = new List <int>();
}
matrix[xi, yi].Possibles.Add(num);
}
}
}
}
}
}
