How to Match positive and negative values withing subgroups

How to match positive and negative values within subgroups

Requirement:

The user has a sheet which contains credits and debits for several accounts:

Customer	Amount
ABC	2000
XYZ	3000
XYZ	1000
ABC	1000
ABC	-5000
XYZ	1000

The user needs to match negative and positive values within each account and highlight them.

Solution:

Code:

Sub x()
  
Dim rFind As Range, sAddr As String, r As Range, s() As String, i As Long, a, b
 
With Range("A2", Range("A" & Rows.Count).End(xlUp))
    ReDim s(1 To 2 * .Count)
    For Each r In .Cells
        Set rFind = .Find(What:=r, After:=r, LookAt:=xlWhole, searchdirection:=xlNext, _
                          MatchCase:=False, SearchFormat:=False)
        If Not rFind Is Nothing Then
            sAddr = rFind.Address
            Do
                If r.Offset(, 1) = -1 * rFind.Offset(, 1) Then
                    a = Application.Match(r.Address, Application.Index(s, 1, 0), 0)
                    b = Application.Match(rFind.Address, Application.Index(s, 1, 0), 0)
                    If Not IsNumeric(a) And Not IsNumeric(b) Then
                            r.Resize(, 2).Interior.Color = vbYellow
                            rFind.Resize(, 2).Interior.Color = vbYellow
                             i = i + 1
                            s(i) = r.Address
                            s(i + 1) = rFind.Address
                            i = i + 1
                            Exit Do
                    End If
                End If
                Set rFind = .FindNext(rFind)
            Loop While rFind.Address <> sAddr And rFind.Address <> r.Address
        End If
    Set rFind = Nothing
    sAddr = ""
    Next r
End With
     
End Sub

Obtained from the OzGrid Help Forum.

Solution provided by StephenR.