#define max(a, b) iif((a) > (b), (a), (b))

Dim Shared As Integer suff(), bmBc(), bmGs()

Sub preBmBc(pat As String)
    Dim As Integer m = Len(pat), i
    Redim bmBc(m)
    For i = 1 To m-1
        bmBc(Cint(pat[i])) = m - i
    Next
End Sub

Sub suffixes(pat As String)
    Dim As Integer m = Len(pat), g = m, i, f
    Redim suff(m)
    suff(m) = m
    For i = m-1 To 1 Step -1
        If i > g And suff(i + m - f) < i - g Then
            suff(i) = suff(i + m - f)
        Else
            If i < g Then g = i
            f = i
            While g >= 1 And pat[g] = pat[g + m - f]
                g -= 1
            Wend
            suff(i) = f - g
        End If
    Next
End Sub

Sub preBmGs(pat As String)
    Dim As Integer m = Len(pat), j = 1, i
    Redim suff(m)
    Redim bmGs(m)
    For i = m To 1 Step -1
        If suff(i) = i Then
            While j < m - i
                If bmGs(j) = m Then bmGs(j) = m - i
                j += 1
            Wend
        End If
    Next
    For i = 1 To m-1
        bmGs(m - suff(i)) = m - i
    Next
End Sub

Sub BM(pat As String, s As String, case_insensitive As Boolean = False)
    Dim As String pins = "'" & pat & "' in " & "'" & s & "'"
    If case_insensitive Then
        pat = Lcase(pat)
        s = Lcase(s)
    End If

    ' Preprocessing
    preBmGs(pat)
    preBmBc(pat)

    ' Searching
    Dim As Integer j = 0, n = Len(s), m = Len(pat), i = m

    While j <= n - m
        i -= 1
        If pat[i] <> s[i+j] Then Exit While
        j += Iif(i < 1, bmGs(0), max(bmGs(i), bmBc(Len(s[i+j]) - m + i)))
    Wend

    Dim As Integer many = Instr(s, pat)
    Dim As String tmp = ""

    If Not many > 0 Then
        Print "No "; pins
    Else
        Do While many > 0    'if not found loop will be skipped
            tmp &= Str(many) & ","
            many = Instr(many + 1, s, pat)
        Loop
        Print Using "Found & at indices [&]"; pins; tmp & Chr(8)
    End If
End Sub

BM("GCAGAGAG","GCATCGCAGAGAGTATACAGTACG")
BM("TCTA","GCTAGCTCTACGAGTCTA")
BM("TAATAAA","GGCTATAATGCGTA")
BM("word","there would have been a time for such a word")
BM("needle","needle need noodle needle")
Const book = "InhisbookseriesTheArtofComputerProgrammingpublishedbyAddisonWesley" + _
"DKnuthusesanimaginarycomputertheMIXanditsassociatedmachinecodeand" + _
"assemblylanguagestoillustratetheconceptsandalgorithmsastheyarepresented"
BM("put",book)
BM("and",book)
Const farm = "Nearby farms grew a half acre of alfalfa on the dairy's behalf, with " + _
"bales of all that alfalfa exchanged for milk."
BM("alfalfa",farm)

Sleep