VBScript で Project Euler Problem 4

昨日の続き
４桁の回文は

で、１１の倍数だから、

	99	98	97	96	95	94	93	92	91
99	9801	9702	9603	9504	9405	9306	9207	9108	9009
98		9604	9506	9408	9310	9212	9114	9016
97			9409	9312	9215	9118	9021
96				9216	9120	9024
95					9025
94
93
92
91

Option Explicit

Private loop_cnt: loop_cnt = 0
Private cnt:      cnt      = 0

Call main

WScript.Echo "ループ回数      = " & CStr(loop_cnt)
WScript.Echo "回文数 判定回数 = " & CStr(cnt)

Private Sub main()
    Dim i
    For i = 99 To 90 Step -1
        Dim x: x = i
        Dim y: y = i
        Do
            loop_cnt = loop_cnt + 1

            Dim n: n = x * y
            Dim s: s = CStr(n)
            WScript.Echo CStr(x) & " * " & CStr(y) & " = " & s

            cnt = cnt + 1
            If s = StrReverse(s) Then
                Exit Sub
            End If

            x = x + 1
            if x > 99 Then Exit Do
            y = y - 1
        Loop
        WScript.Echo ""

        x = i
        y = i - 1
        Do
            loop_cnt = loop_cnt + 1

            n = x * y
            s = CStr(n)
            WScript.Echo CStr(x) & " * " & CStr(y) & " = " & s

            cnt = cnt + 1
            If s = StrReverse(s) Then
                Exit Sub
            End If

            x = x + 1
            if x > 99 Then Exit Do
            y = y - 1
        Loop
        WScript.Echo ""
    Next
End Sub

D:\Project Euler\Problem 004>cscript //nologo 006.vbs
99 * 99 = 9801

99 * 98 = 9702

98 * 98 = 9604
99 * 97 = 9603

98 * 97 = 9506
99 * 96 = 9504

97 * 97 = 9409
98 * 96 = 9408
99 * 95 = 9405

97 * 96 = 9312
98 * 95 = 9310
99 * 94 = 9306

96 * 96 = 9216
97 * 95 = 9215
98 * 94 = 9212
99 * 93 = 9207

96 * 95 = 9120
97 * 94 = 9118
98 * 93 = 9114
99 * 92 = 9108

95 * 95 = 9025
96 * 94 = 9024
97 * 93 = 9021
98 * 92 = 9016
99 * 91 = 9009
ループ回数      = 25
回文数 判定回数 = 25

のうち、
99 * n
以外のものは、１１の倍数にならないので計算する必要がない。

Option Explicit

Private loop_cnt: loop_cnt = 0
Private cnt:      cnt      = 0

Call main

WScript.Echo "ループ回数      = " & CStr(loop_cnt)
WScript.Echo "回文数 判定回数 = " & CStr(cnt)

Private Sub main()
    Dim i
    For i = 99 To 90 Step -1
        Dim x: x = i
        Dim y: y = i
        Do
            loop_cnt = loop_cnt + 1

            If (x mod 11 = 0) Or (y mod 11 = 0) Then
                Dim n: n = x * y
                Dim s: s = CStr(n)
                WScript.Echo CStr(x) & " * " & CStr(y) & " = " & s

                cnt = cnt + 1
                If s = StrReverse(s) Then
                    Exit Sub
                End If
            End If

            x = x + 1
            if x > 99 Then Exit Do
            y = y - 1
        Loop

        x = i
        y = i - 1
        Do
            loop_cnt = loop_cnt + 1

            If (x mod 11 = 0) Or (y mod 11 = 0) Then
                n = x * y
                s = CStr(n)
                WScript.Echo CStr(x) & " * " & CStr(y) & " = " & s

                cnt = cnt + 1
                If s = StrReverse(s) Then
                    Exit Sub
                End If
            End If

            x = x + 1
            if x > 99 Then Exit Do
            y = y - 1
        Loop
    Next
End Sub

D:\Project Euler\Problem 004>cscript //nologo 007.vbs
99 * 99 = 9801
99 * 98 = 9702
99 * 97 = 9603
99 * 96 = 9504
99 * 95 = 9405
99 * 94 = 9306
99 * 93 = 9207
99 * 92 = 9108
99 * 91 = 9009
ループ回数      = 25
回文数 判定回数 = 9

	99	98	97	96	95	94	93	92	91
99	9801	9702	9603	9504	9405	9306	9207	9108	9009

同様に６桁の回文も

で、１１の倍数だから

Option Explicit

Private loop_cnt: loop_cnt = 0
Private cnt:      cnt      = 0

Call main

WScript.Echo "ループ回数      = " & CStr(loop_cnt)
WScript.Echo "回文数 判定回数 = " & CStr(cnt)

Private Sub main()
    Dim i
    For i = 999 To 900 Step -1
        Dim x: x = i
        Dim y: y = i
        Do
            loop_cnt = loop_cnt + 1

            If (x mod 11 = 0) Or (y mod 11 = 0) Then
                Dim n: n = x * y
                Dim s: s = CStr(n)

                cnt = cnt + 1
                If s = StrReverse(s) Then
                    WScript.Echo CStr(x) & " * " & CStr(y) & " = " & s
                    Exit Sub
                End If
            End If

            x = x + 1
            if x > 999 Then Exit Do
            y = y - 1
        Loop

        x = i
        y = i - 1
        Do
            loop_cnt = loop_cnt + 1

            If (x mod 11 = 0) Or (y mod 11 = 0) Then
                n = x * y
                s = CStr(n)

                cnt = cnt + 1
                If s = StrReverse(s) Then
                    WScript.Echo CStr(x) & " * " & CStr(y) & " = " & s
                    Exit Sub
                End If
            End If

            x = x + 1
            if x > 999 Then Exit Do
            y = y - 1
        Loop
    Next
End Sub

D:\Project Euler\Problem 004>cscript //nologo 008.vbs
993 * 913 = 906609
ループ回数      = 2203
回文数 判定回数 = 352

ロジックは一緒だけど、ソースを少し整理した

Option Explicit

Private loop_cnt: loop_cnt = 0
Private cnt:      cnt      = 0

Call main

WScript.Echo "ループ回数      = " & CStr(loop_cnt)
WScript.Echo "回文数 判定回数 = " & CStr(cnt)

Private Sub main()
    Dim i, j
    For i = 999 To 100 Step -1
        For j = 0 To 1
            Dim x: x = i
            Dim y: y = i - j
            Do
                loop_cnt = loop_cnt + 1

                If (x mod 11 = 0) Or (y mod 11 = 0) Then
                    cnt = cnt + 1

                    Dim s: s = CStr(x * y)
                    If s = StrReverse(s) Then
                        WScript.Echo CStr(x) & " * " & CStr(y) & " = " & s
                        Exit Sub
                    End If
                End If

                x = x + 1
                y = y - 1
            Loop Until (x > 999)
        Next
    Next
End Sub

D:\Project Euler\Problem 004>cscript //nologo 009.vbs
993 * 913 = 906609
ループ回数      = 2203
回文数 判定回数 = 352