Public Class Form1
    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        Randomize()
        Dim str As String = " "
        Dim CaseVide As String = 15
        Dim random As New Random()
        Dim rnd As Integer
        For x As Integer = 0 To 100
            For j As Integer = 0 To 15

                Dim i As Integer = j
                If (CaseVide = j) Then

                    If i > 3 And i < 12 Then
                        rnd = random.Next(0, 4)
                        If i Mod 4 = 3 Then
                            Select Case rnd
                                Case 0
                                    str += "" & CInt(i - 4)
                                Case 1
                                    str += "" & CInt(i - 3)
                                Case 2
                                    str += "" & CInt(i - 1)
                                Case Else
                                    str += "" & CInt(i + 4)
                            End Select
                        ElseIf i Mod 4 = 0 Then
                            Select Case rnd
                                Case 0
                                    str += "" & CInt(i - 4)
                                Case 1
                                    str += "" & CInt(i - 1)
                                Case 2
                                    str += "" & CInt(i + 3)
                                Case Else
                                    str += "" & CInt(i + 4)
                            End Select
                        Else
                            Select Case rnd
                                Case 0
                                    str += "" & CInt(i - 4)
                                Case 1
                                    str += "" & CInt(i - 1)
                                Case 2
                                    str += "" & CInt(i + 1)
                                Case Else
                                    str += "" & CInt(i + 4)
                            End Select
                        End If
                    ElseIf i <= 3 Then
                        rnd = random.Next(0, 3)
                        If i = 0 Then
                            Select Case rnd
                                Case 0
                                    str += "2"
                                Case 1
                                    str += "4"
                                Case 2
                                    str += "5"
                            End Select
                        ElseIf i = 3 Then
                            Select Case rnd
                                Case 0
                                    str += "1"
                                Case 1
                                    str += "3"
                                Case 2
                                    str += "8"
                            End Select
                        Else
                            rnd = random.Next(0, 3)
                            Select Case rnd
                                Case 0
                                    str += "" & CInt(i - 1)
                                Case 1
                                    str += "" & CInt(i + 1)
                                Case Else
                                    str += "" & CInt(i + 4)
                            End Select
                        End If
                    ElseIf i >= 12 Then
                        rnd = random.Next(0, 3)
                        If i = 12 Then
                            Select Case rnd
                                Case 0
                                    str += "9"
                                Case 1
                                    str += "14"
                                Case 2
                                    str += "16"
                            End Select
                        ElseIf i = 15 Then
                            Select Case rnd
                                Case 0
                                    str += "12"
                                Case 1
                                    str += "13"
                                Case 2
                                    str += "15"
                            End Select
                        Else
                            rnd = random.Next(0, 3)
                            Select Case rnd
                                Case 0
                                    str += "" & CInt(i - 1)
                                Case 1
                                    str += "" & CInt(i + 1)
                                Case Else
                                    str += "" & CInt(i + 4)
                            End Select
                        End If
                    End If
                    str += " "
                    CaseVide = CInt(str.ElementAt(str.Length - 2) & (str.ElementAt(str.Length - 1)))
                End If
            Next j
        Next x
        MsgBox(str)
    End Sub

    Private Sub TextBox1_TextChanged(sender As Object, e As EventArgs) Handles TextBox1.TextChanged

    End Sub
End Class