Data commit

Task/Fraction-reduction/Visual-Basic-.NET/fraction-reduction.vb

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