Modifying a sub that combines and sums duplicate rows - excel

Question

If this sub finds finds matching values in column A, it will merge those two values into one row, and then sum columns B & C into run row.
I've been trying to change it so that for this to happen, it needs to find a match in columns A & B, then C & D will be summed.
For example:
A A 5 5
A A 5 5
A B 6 1
Will Become
A A 10 10
A B 6 1
Sub Consolidate()
Application.ScreenUpdating = False
Dim s As Worksheet, last_row As Long
Dim row As Long
Dim col As Integer, v, m
Set s = Worksheets("Sheet12")
s.Activate
last_row = s.Cells(s.rows.Count, 1).End(xlUp).row 'find the last row with data
For row = last_row To 3 Step -1
v = s.Cells(row, "A").Value
m = Application.Match(v, s.Columns("A"), 0) 'find first match to this row
If m < row Then 'earlier row?
'combine rows `row` and `m`
s.Cells(m, "B").Value = s.Cells(m, "B").Value + s.Cells(row, "B").Value
s.Cells(m, "C").Value = s.Cells(m, "C").Value + s.Cells(row, "C").Value
s.rows(row).Delete
End If 'matched a different row
Next row
End Sub

Answer 1

Slight modification using a dictionary:
Sub Consolidate()
Application.ScreenUpdating = False
Dim s As Worksheet, last_row As Long
Dim row As Long, dict As Object, k As String, m As Long
Set dict = CreateObject("scripting.dictionary") 'for tracking A+B vs first row occurence
Set s = Worksheets("Sheet12")
s.Activate
last_row = s.Cells(s.Rows.Count, 1).End(xlUp).row 'find the last row with data
'map all the A+B combinations to the first row they occur on
For row = 3 To last_row
k = s.Cells(row, "A").Value & "~~" & s.Cells(row, "B").Value
If Not dict.exists(k) Then dict.Add k, row
Next row
For row = last_row To 3 Step -1
k = s.Cells(row, "A").Value & "~~" & s.Cells(row, "B").Value
m = dict(k) 'find first match to this row from the dictionary
If m < row Then 'earlier row?
'combine rows `row` and `m`
s.Cells(m, "C").Value = s.Cells(m, "C").Value + s.Cells(row, "C").Value
s.Cells(m, "D").Value = s.Cells(m, "D").Value + s.Cells(row, "D").Value
s.Rows(row).Delete
End If 'matched a different row
Next row
End Sub