How to sum values in variable range in VBA? - vba

Question

I have a table as shown below.
In column C I would like to Sum values from column A if they have the same index (column B). I would like to put sum result for all the rows if they have same index (as shown in column D).
Unfortunately the range of values with same index is variable and my macro can sum values just with 2 indexes. Can anyone help with it, please? Thanks!
Sub example()
Dim ws As Worksheet
Dim LastRow As Long
Dim n, i As Integer
Set ws = ActiveWorkbook.Sheets("Sheet2")
ws.Select
LastRow = Sheets("Sheet2").Range("A" & Sheets("Sheet2").Rows.Count).End(xlUp).Row
Range("C3:C" & LastRow).Select
Selection.ClearContents
For i = 3 To LastRow
If Range("B" & i + 1) - Range("B" & i) = 0 Then
Range("C" & i) = Range("A" & i + 1) + Range("A" & i)
Else
Range("C" & i) = Range("C" & i - 1)
End If
Next i
End Sub

Answer 1

Here's one way:
Sub example()
Dim ws As Worksheet
Dim LastRow As Long
Set ws = ActiveWorkbook.Sheets("Sheet2")
LastRow = ws.Range("A" & ws.Rows.Count).End(xlUp).Row
With ws.Range("C3:C" & LastRow)
.ClearContents
.Value = ws.Evaluate("INDEX(SUMIF(B3:B" & LastRow & ",B3:B" & LastRow & ",A3:A" & LastRow & "),)")
End With
End Sub