filling of cells using vba with simple criteria

Sub Fill_Blanks_In_Column_A()
Application.ScreenUpdating = False
Dim i As Long
Dim Lastrow As Long
Lastrow = Cells(Rows.Count, "A").End(xlUp).Row
    For i = 4 To Lastrow
        If Cells(i, 1).Value = "" Then Cells(i, 1).Value = "H"
    Next
Application.ScreenUpdating = True
End Sub

Sub FillBlanksWithLetterH()
  Dim LastRow As Long
  LastRow = Cells.Find("*", , xlValues, , xlRows, xlPrevious).Row
  Range("A[B][COLOR="#FF0000"]2[/COLOR][/B]:A" & LastRow).SpecialCells(xlBlanks).Value = "H"
End Sub

[table="width: 500"]
[tr]
	[td]Sub FillBlanksWithLetterH()
  Dim R As Long, OnOff As Boolean, Data As Variant
  Data = Range("A1", Columns("A").Find("C", , xlValues, xlWhole, xlRows, xlPrevious, False, , False))
  For R = 1 To UBound(Data)
    If InStr(1, " B C ", " " & Data(R, 1) & " ", vbTextCompare) Then OnOff = UCase(Data(R, 1)) = "B"
    If OnOff Then
      If Data(R, 1) = "" Then Data(R, 1) = "H"
    End If
  Next
  Range("A1").Resize(UBound(Data)) = Data
End Sub[/td]
[/tr]
[/table]