public static void SearchColumnForSingleCandidates(this Grid grid)
{
for (int col = 0; col < grid.GridSize; col++)
{
for (int value = 1; value <= grid.GridSize; value++)
{
// that value already exists in the col
if (Array.Exists(grid.GetColumn(col), element => element == value))
{
continue;
}
int result = grid.CheckColForValueInOptions(col, value);
if (result != -1)
{
grid.SolveCell(result, col, value);
grid.UpdateNeighbours(result, col);
}
}
}
}