Imports System.ComponentModel


Public Class Form1
    Private Structure TestsInfo
        Public ReadOnly start As Long
        Public ReadOnly last As Long
        Public ReadOnly expected As Long


        Public Sub New(ByVal start As Long,
                ByVal last As Long,
                ByVal expected As Long)
            Me.start = start
            Me.last = last
            Me.expected = expected
        End Sub
    End Structure


    Private Class BenchmarkResult
        Private m_index As Integer
        Private m_name As String
        Private m_ms As Double
        Private m_perf As Double


        Public Sub New(ByVal index As Integer,
                ByVal name As String,
                ByVal ms As Double)
            m_index = index
            m_name = name
            m_ms = ms
        End Sub


        Public Sub CalcPerf(ByVal avgElapsed As Double)
            m_perf = avgElapsed / m_ms
        End Sub


        Public Property Index As Integer
            Get
                Return m_index
            End Get
            Set(ByVal value As Integer)
                m_index = value
            End Set
        End Property


        Public Property Name As String
            Get
                Return m_name
            End Get
            Set(ByVal value As String)
                m_name = value
            End Set
        End Property


        Public Property Ms As Double
            Get
                Return m_ms
            End Get
            Set(ByVal value As Double)
                m_ms = value
            End Set
        End Property


        Public ReadOnly Property Performance As String
            Get
                Return String.Format("{0:f2}%", 100 * m_perf)
            End Get
        End Property
    End Class


    ' start, last, expected
    Private ReadOnly tests As TestsInfo() = {
        New TestsInfo(1, 1, 1L),
        New TestsInfo(1, 2, 3L),
        New TestsInfo(1, 3, 3L),
        New TestsInfo(1, 10, 37L),
        New TestsInfo(1, 13, 48L),
        New TestsInfo(1, 20, 134L),
        New TestsInfo(3, 3, 0),
        New TestsInfo(3, 4, 4L),
        New TestsInfo(3, 5, 9L),
        New TestsInfo(3, 6, 9L),
        New TestsInfo(3, 9, 24L),
        New TestsInfo(13, 13, 0),
        New TestsInfo(13, 23, 108L),
        New TestsInfo(100, 1000, 249976L),
        New TestsInfo(1, 100, 2872L),
        New TestsInfo(3, 103, 2970L),
        New TestsInfo(123, 456, 32130L),
        New TestsInfo(300, 4000, 2192728L),
        New TestsInfo(332, 3332, 2188728L),
        New TestsInfo(777, 7777, 12814264L),
        New TestsInfo(999, 9999, 22425984L),
        New TestsInfo(1, 999999, 183707816292L)
    }
    Private fnCalc As Func(Of Long, Long, Long)
    Private Const NUM_BENCHMARK As Integer = 50




    Private Sub Button1_Click() Handles Button1.Click
        Dim actions As Func(Of Long, Long, Long)() = {
                AddressOf Calc1,
                AddressOf Calc2,
                AddressOf Calc3
            },
            ubActions = actions.GetUpperBound(0),
            benchmarkElapsed(ubActions) As Double,
            avgElapsed As Double = 0,
            lstResult As IBindingList =
                New BindingList(Of BenchmarkResult)


        Me.Text = "Benchmarking...Please wait"


        ' benchmark
        For i As Integer = 0 To ubActions
            fnCalc = actions(i)
            benchmarkElapsed(i) = Benchmark(AddressOf DoCalc, NUM_BENCHMARK)
            avgElapsed += benchmarkElapsed(i)
        Next


        avgElapsed /= (ubActions + 1)


        ' output the result
        For i As Integer = 0 To ubActions
            Dim benchmarkResult As New BenchmarkResult(i,
                actions(i).Method.Name,
                benchmarkElapsed(i))


            benchmarkResult.CalcPerf(avgElapsed)
            lstResult.Add(benchmarkResult)
        Next


        ' configure datagridview
        DataGridView1.DataSource = lstResult
        DataGridView1.AutoResizeRows()
        DataGridView1.AutoResizeColumns()


        Me.Text = "Completed"
    End Sub


    Private Function Benchmark(ByVal fn As Action,
                               ByVal testTimes As Integer) As Double
        Dim sw As New Stopwatch,
            times As Integer = testTimes


        sw.Start()


        While times <> 0
            fn()
            times -= 1
        End While


        sw.Stop()
        Return sw.ElapsedMilliseconds / testTimes
    End Function


    Private Sub DoCalc()
        Dim ret As Long


        For i As Integer = 0 To tests.GetUpperBound(0)
            Dim test As TestsInfo = tests(i)


            ret = fnCalc(test.start, test.last)
            Debug.Assert(test.expected = ret,
                String.Format("Wrong result, expected {0} but got {1}. " &
                    "Index is {2}, from {3} to {4}",
                    test.expected,
                    ret,
                    i,
                    test.start,
                    test.last)
                )
        Next
    End Sub


    Private Function Calc1(ByVal numStart As Long,
            ByVal numLast As Long) As Long
        Dim sum As Long = 0


        For i As Long = numStart To numLast
            Dim s As String = i.ToString()


            If 0 <> i Mod 3 AndAlso
                -1 = s.IndexOf("3"c) Then
                sum += i
            End If
        Next


        Return sum
    End Function


    Private Function Calc2(ByVal numStart As Long,
            ByVal numLast As Long) As Long
        Dim sum As Long = 0,
            start As Long,
            last As Long


        For i As Long = 1 To 2
            start = ((numStart - 1 + i) \ 3 + 1) * 3 - i
            last = ((numLast + i) \ 3) * 3 - i


            For j As Long = start To last Step 3
                Dim s As String = j.ToString()


                If -1 = s.IndexOf("3"c) Then
                    sum += j
                End If
            Next
        Next


        Return sum
    End Function


    Private Function Calc3(ByVal numStart As Long,
            ByVal numLast As Long) As Long
        Dim sum As Long = 0


        For i As Long = 1 To 2
            Dim start As Long = ((numStart - 1 + i) \ 3 + 1) * 3 - i,
                last As Long = ((numLast + i) \ 3) * 3 - i


            For j As Long = start To last Step 3
                Dim k As Long = j


                Do
                    If 3 = k Mod 10 Then
                        Exit Do
                    End If


                    k \= 10
                Loop While 0 <> k


                If 0 = k Then
                    sum += j
                End If
            Next
        Next


        Return sum
    End Function


End Class