Imports System.IO

Partial Class SimAnnealing
    Inherits System.Web.UI.Page

    Dim rand As Random = New Random
    Dim filename As String = Server.MapPath("tsp.txt")
    Dim dimension As Integer = 15
    Dim data As Double(,)
    Dim incumbent As String
    Dim incDist As Integer

    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load

    End Sub

    Protected Sub btn_start_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btn_start.Click
        computeData()

        Dim i As Integer
        Dim curr() As Integer = New Integer(14) {}
        setCurrent(curr)
        incumbent = recoverSolution(curr)
        incDist = computeDistance(curr)
        Dim nxt() As Integer = New Integer(14) {}
        For i = 0 To curr.Length - 1
            nxt(i) = New Integer
        Next
        Dim iteration As Integer = -1
        Dim proba As Double
        Dim alpha As Double = txt_alpha.Text
        Dim temperature As Double = txt_temp.Text
        Dim epsilon As Double = txt_epsilon.Text
        Dim delta As Double
        Dim distance As Double = computeDistance(curr)
        Dim c1 As LineChartAbs = New LineChartAbs(550, 550, Page)
        Dim route As String

        Do While (temperature > epsilon)
            iteration = iteration + 1
            computeNext(curr, nxt)
            delta = computeDistance(nxt) - distance
            If (delta < 0) Then
                assign(curr, nxt)
                distance = distance + delta
            Else
                proba = rand.NextDouble
                Dim test As Double = Math.Exp(-delta / temperature)
                If (proba < Math.Exp(-delta / temperature)) Then
                    assign(curr, nxt)
                    distance = distance + delta
                End If
            End If

            'Keep track of best solution
            If (computeDistance(curr) < incDist) Then
                incumbent = recoverSolution(curr)
                incDist = computeDistance(curr)
            End If

            temperature = temperature * alpha
            If ((iteration Mod 200) = 0) Then
                'Add every 200th value to the graph
                c1.AddValue(iteration, distance, "", "")
                c1.AddValue2(iteration, incDist, "", "")
            End If

        Loop
        c1.Title = "      Traveling Salesman Problem Using Simulated Annealing      "

        c1.Xorigin = 0
        c1.ScaleX = iteration
        c1.Xdivs = 50

        c1.Yorigin = 0
        c1.ScaleY = 100
        c1.Ydivs = 50

        route = recoverSolution(curr)

        c1.Draw("The best route is " & incumbent & ", with a distance of " & incDist & ".", 450)        'lbl_solution.Text = "The best distance is " & distance & "."

    End Sub

    Private Sub assign(ByRef c() As Integer, ByRef n() As Integer)
        Dim i As Integer
        For i = 0 To c.Length - 1
            c(i) = n(i)
        Next
    End Sub

    Private Sub computeNext(ByRef c() As Integer, ByRef n() As Integer)
        Dim i, i1, i2, aux As Integer
        For i = 0 To c.Length - 1
            n(i) = c(i)
        Next
        i1 = rand.Next(14) + 1
        i2 = rand.Next(14) + 1
        aux = n(i1)
        n(i1) = n(i2)
        n(i2) = aux
    End Sub

    Private Sub setCurrent(ByRef c() As Integer)
        Dim i, temp As Integer
        Dim isSet As BitArray = New BitArray(15)

        For i = 0 To c.Length - 1
            temp = rand.Next(0, 15)
            Do While (isSet(temp))
                temp = rand.Next(0, 15)
            Loop
            c(i) = temp
            isSet(temp) = True
        Next

    End Sub

    Private Function recoverSolution(ByVal c() As Integer) As String
        Dim route As String = ""
        Dim last As String
        Dim i, caseInt As Integer
        For i = 0 To c.Length - 1
            caseInt = c(i)
            Select Case caseInt
                Case 0
                    route = route + "A"
                Case 1
                    route = route + "B"
                Case 2
                    route = route + "C"
                Case 3
                    route = route + "D"
                Case 4
                    route = route + "E"
                Case 5
                    route = route + "F"
                Case 6
                    route = route + "G"
                Case 7
                    route = route + "H"
                Case 8
                    route = route + "I"
                Case 9
                    route = route + "J"
                Case 10
                    route = route + "K"
                Case 11
                    route = route + "L"
                Case 12
                    route = route + "M"
                Case 13
                    route = route + "N"
                Case 14
                    route = route + "O"
            End Select
        Next
        last = route.Substring(0, 1)
        route = route + last
        Return route
    End Function
    Public Function computeDistance(ByRef t() As Integer) As Integer
        Dim distance As Integer
        Dim str As String
        Dim i As Integer

        For i = 0 To (dimension - 2)
            str = t(i)
            str = t(i + 1)
            str = Convert.ToInt32(data(t(i), t(i + 1)))
            distance = distance + Convert.ToInt32(data(t(i), t(i + 1)))
        Next

        distance = distance + Convert.ToInt32(data(t(dimension - 1), t(0)))

        Return distance
    End Function

    Public Function getData() As Double(,)
        Return data
    End Function

    Public Sub computeData()
        Dim line As String
        Dim i, j As Integer
        data = New Double(dimension, dimension) {}

        Try
            Dim objStreamReader As StreamReader
            objStreamReader = File.OpenText(filename)

            For i = 0 To dimension - 1
                line = objStreamReader.ReadLine
                Dim st As String() = line.Split(" ")
                For j = 0 To dimension - 1
                    data(i, j) = Double.Parse(st(j))
                Next
            Next

        Catch ex As Exception
            Console.WriteLine(ex.ToString)
        End Try

    End Sub
End Class