97 lines
3.2 KiB
VB.net
97 lines
3.2 KiB
VB.net
Module Module1
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Function IndexOf(n As Integer, s As Integer()) As Integer
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For ii = 1 To s.Length
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Dim i = ii - 1
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If s(i) = n Then
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Return i
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End If
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Next
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Return -1
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End Function
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Function GetDigits(n As Integer, le As Integer, digits As Integer()) As Boolean
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While n > 0
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Dim r = n Mod 10
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If r = 0 OrElse IndexOf(r, digits) >= 0 Then
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Return False
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End If
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le -= 1
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digits(le) = r
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n \= 10
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End While
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Return True
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End Function
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Function RemoveDigit(digits As Integer(), le As Integer, idx As Integer) As Integer
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Dim pows = {1, 10, 100, 1000, 10000}
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Dim sum = 0
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Dim pow = pows(le - 2)
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For ii = 1 To le
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Dim i = ii - 1
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If i = idx Then
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Continue For
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End If
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sum += digits(i) * pow
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pow \= 10
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Next
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Return sum
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End Function
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Sub Main()
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Dim lims = {{12, 97}, {123, 986}, {1234, 9875}, {12345, 98764}}
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Dim count(5) As Integer
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Dim omitted(5, 10) As Integer
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Dim upperBound = lims.GetLength(0)
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For ii = 1 To upperBound
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Dim i = ii - 1
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Dim nDigits(i + 2 - 1) As Integer
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Dim dDigits(i + 2 - 1) As Integer
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Dim blank(i + 2 - 1) As Integer
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For n = lims(i, 0) To lims(i, 1)
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blank.CopyTo(nDigits, 0)
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Dim nOk = GetDigits(n, i + 2, nDigits)
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If Not nOk Then
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Continue For
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End If
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For d = n + 1 To lims(i, 1) + 1
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blank.CopyTo(dDigits, 0)
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Dim dOk = GetDigits(d, i + 2, dDigits)
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If Not dOk Then
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Continue For
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End If
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For nixt = 1 To nDigits.Length
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Dim nix = nixt - 1
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Dim digit = nDigits(nix)
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Dim dix = IndexOf(digit, dDigits)
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If dix >= 0 Then
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Dim rn = RemoveDigit(nDigits, i + 2, nix)
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Dim rd = RemoveDigit(dDigits, i + 2, dix)
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If (n / d) = (rn / rd) Then
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count(i) += 1
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omitted(i, digit) += 1
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If count(i) <= 12 Then
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Console.WriteLine("{0}/{1} = {2}/{3} by omitting {4}'s", n, d, rn, rd, digit)
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End If
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End If
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End If
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Next
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Next
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Next
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Console.WriteLine()
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Next
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For i = 2 To 5
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Console.WriteLine("There are {0} {1}-digit fractions of which:", count(i - 2), i)
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For j = 1 To 9
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If omitted(i - 2, j) = 0 Then
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Continue For
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End If
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Console.WriteLine("{0,6} have {1}'s omitted", omitted(i - 2, j), j)
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Next
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Console.WriteLine()
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Next
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End Sub
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End Module
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