基本情報技術者試験H25秋期午後問8（疑似言語）VBAプログラム

Sub main()
    Dim Plaindata() As String
    Dim Plength As Integer, Compresseddata(20) As String, Clength As Integer
    Dim Str As String
    Str = "ABCDEFABCDABCDEF"
    ReDim Plaindata(0 To Len(Str) - 1)
    For i = 1 To UBound(Plaindata) + 1
        Plaindata(i - 1) = Mid(Str, i, 1)
'       Debug.Print "Plaindata("; i - 1; ")="; Plaindata(i - 1)
    Next i
    Plength = Len(Str)

    Call Compress(Plaindata, Plength, Compresseddata, Clength)

    For i = 1 To UBound(Compresseddata)
        Debug.Print Compresseddata(i - 1)
    Next i

End Sub

Sub Compress(ByRef Plaindata() As String, ByVal Plength As Integer, ByRef Compresseddata() As String, ByVal Clength As Integer)
    Dim Esym As String
    Dim Pindex As Integer, Cindex As Integer
    Dim Maxfitnum As Integer, Maxdistance As Integer, Distance As Integer, Fitnum As Integer
    Dim ABCD As String
    ABCD = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"

    If Plength >= 1 Then
        Esym = "$"
        Pindex = 0
        Cindex = 0
        Do While (Pindex < Plength) And (Pindex < 4)
            Compresseddata(Cindex) = Plaindata(Pindex)
            Debug.Print "Pindex="; Pindex, "Plaindata()="; Plaindata(Pindex), "cindex="; Cindex, "Compresseddata()="; Compresseddata(Cindex)
            Cindex = Cindex + 1
            Pindex = Pindex + 1
        Loop

        Do While (Pindex < Plength)
            Maxfitnum = -1
            Maxdistance = -1
            Distance = 4
            Do While ((Distance <= 26) And (Pindex - Distance >= 0))
                Fitnum = 0
                Do While ((Fitnum < Distance) And ((Pindex + Fitnum) < Plength))
                    If Plaindata(Pindex + Fitnum) <> Plaindata(Pindex + Fitnum - Distance) Then
                        Debug.Print "Pindex="; Pindex, "Fitnum="; Fitnum, "Plaindata()="; Plaindata(Pindex + Fitnum), "Distance="; Distance, ";Plaindata()="; Plaindata(Pindex + Fitnum - Distance)
                        Exit Do
                    End If
                    Debug.Print "Pindex="; Pindex, "Fitnum="; Fitnum, "Plaindata()="; Plaindata(Pindex + Fitnum), "Distance="; Distance, "Plaindata()="; Plaindata(Pindex + Fitnum - Distance)
                    Fitnum = Fitnum + 1
                Loop

                If (Fitnum >= 4) And (Maxfitnum < Fitnum) Then
                    Maxfitnum = Fitnum
                    Maxdistance = Distance
                End If
                Distance = Distance + 1
            Loop
            If Maxfitnum = -1 Then
                Compresseddata(Cindex) = Plaindata(Pindex)
                Debug.Print "Pindex="; Pindex, "Plaindata()="; Plaindata(Pindex), "cindex="; Cindex, "Compresseddata()="; Compresseddata(Cindex)
                Cindex = Cindex + 1
                Pindex = Pindex + 1
            Else
                Compresseddata(Cindex) = Esym
                Compresseddata(Cindex + 1) = Mid(ABCD, Maxdistance, 1)
                Compresseddata(Cindex + 2) = Mid(ABCD, Maxfitnum, 1)
                Debug.Print "Pindex="; Pindex, "Plaindata()="; Plaindata(Pindex), "cindex="; Cindex, "Compresseddata()="; Compresseddata(Cindex); Compresseddata(Cindex + 1); Compresseddata(Cindex + 2)
                Cindex = Cindex + 3
                Pindex = Pindex + Maxfitnum
            End If
        Loop
        Clength = Cindex
    End If
End Sub

実行結果

Pindex= 0 Plaindata()=A cindex= 0 Compresseddata()=A
Pindex= 1 Plaindata()=B cindex= 1 Compresseddata()=B
Pindex= 2 Plaindata()=C cindex= 2 Compresseddata()=C
Pindex= 3 Plaindata()=D cindex= 3 Compresseddata()=D
Pindex= 4 Fitnum= 0 Plaindata()=E Distance= 4 ;Plaindata()=A
Pindex= 4 Plaindata()=E cindex= 4 Compresseddata()=E
Pindex= 5 Fitnum= 0 Plaindata()=F Distance= 4 ;Plaindata()=B
Pindex= 5 Fitnum= 0 Plaindata()=F Distance= 5 ;Plaindata()=A
Pindex= 5 Plaindata()=F cindex= 5 Compresseddata()=F
Pindex= 6 Fitnum= 0 Plaindata()=A Distance= 4 ;Plaindata()=C
Pindex= 6 Fitnum= 0 Plaindata()=A Distance= 5 ;Plaindata()=B
Pindex= 6 Fitnum= 0 Plaindata()=A Distance= 6 Plaindata()=A
Pindex= 6 Fitnum= 1 Plaindata()=B Distance= 6 Plaindata()=B
Pindex= 6 Fitnum= 2 Plaindata()=C Distance= 6 Plaindata()=C
Pindex= 6 Fitnum= 3 Plaindata()=D Distance= 6 Plaindata()=D
Pindex= 6 Fitnum= 4 Plaindata()=A Distance= 6 ;Plaindata()=E
Pindex= 6 Plaindata()=A cindex= 6 Compresseddata()=$FD
Pindex= 10 Fitnum= 0 Plaindata()=A Distance= 4 Plaindata()=A
Pindex= 10 Fitnum= 1 Plaindata()=B Distance= 4 Plaindata()=B
Pindex= 10 Fitnum= 2 Plaindata()=C Distance= 4 Plaindata()=C
Pindex= 10 Fitnum= 3 Plaindata()=D Distance= 4 Plaindata()=D
Pindex= 10 Fitnum= 0 Plaindata()=A Distance= 5 ;Plaindata()=F
Pindex= 10 Fitnum= 0 Plaindata()=A Distance= 6 ;Plaindata()=E
Pindex= 10 Fitnum= 0 Plaindata()=A Distance= 7 ;Plaindata()=D
Pindex= 10 Fitnum= 0 Plaindata()=A Distance= 8 ;Plaindata()=C
Pindex= 10 Fitnum= 0 Plaindata()=A Distance= 9 ;Plaindata()=B
Pindex= 10 Fitnum= 0 Plaindata()=A Distance= 10 Plaindata()=A
Pindex= 10 Fitnum= 1 Plaindata()=B Distance= 10 Plaindata()=B
Pindex= 10 Fitnum= 2 Plaindata()=C Distance= 10 Plaindata()=C
Pindex= 10 Fitnum= 3 Plaindata()=D Distance= 10 Plaindata()=D
Pindex= 10 Fitnum= 4 Plaindata()=E Distance= 10 Plaindata()=E
Pindex= 10 Fitnum= 5 Plaindata()=F Distance= 10 Plaindata()=F
Pindex= 10 Plaindata()=A cindex= 9 Compresseddata()=$JF
A
B
C
D
E
F
$
F
D
$
J
F