ถ้าต้องการจัดกลุ่มนักเรียนกลุ่มละ 40 คน จาก 100 คน [จนปัญญาจริงๆ]

Imports System.Windows.Forms
Imports System.Collections.Generic

Public Class Form1
    'Private ButtonList As List(Of Button) = New List(Of Button)()
    'Private Const MaxButtonNumber As Integer = 5

    'Private AttachEventButton As Button = New Button()
    'Private DetachEventButton As Button = New Button()

    Dim DisplayBox As ListBox = New ListBox()
    Dim RadioRandomIsOn As RadioButton = New RadioButton()
    Dim RadioRandomIsOff As RadioButton = New RadioButton()

    Dim NumericUpDownTotalStudentPerGroup As NumericUpDown = New NumericUpDown()
    Dim submitButton As Button = New Button()

    Private PassRunOnce As Boolean = False
    Dim myStudentOnGroup As StudentAssignment = New StudentAssignment()

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

        PassRunOnce = False

        Dim allStudent As List(Of String) = New List(Of String)

        For a As Integer = 1 To 100
            allStudent.Add("นักเรียนคนที่ " + a.ToString())
        Next

        InitControl()


        myStudentOnGroup.allStudent = allStudent
        myStudentOnGroup.IsRandom = False
        myStudentOnGroup.StudentPerGroup = 40
        'myStudentOnGroup.OnAssigned()

        RadioRandomIsOn.Checked = myStudentOnGroup.IsRandom
        RadioRandomIsOff.Checked = Not myStudentOnGroup.IsRandom

        NumericUpDownTotalStudentPerGroup.Minimum = 1
        NumericUpDownTotalStudentPerGroup.Maximum = allStudent.Count
        NumericUpDownTotalStudentPerGroup.Value = myStudentOnGroup.StudentPerGroup

        PassRunOnce = True

    End Sub

    Private Sub InitControl()

        Me.Width = 600
        Me.Height = 400
        DisplayBox.Location = New System.Drawing.Point(10, 10)
        DisplayBox.Size = New System.Drawing.Size(300, 300)
        DisplayBox.TabIndex = 0
        Me.Controls.Add(DisplayBox)

        RadioRandomIsOn.AutoSize = True
        RadioRandomIsOn.Location = New System.Drawing.Point(320, 12)
        RadioRandomIsOn.Size = New System.Drawing.Size(90, 17)
        RadioRandomIsOn.TabIndex = 1
        RadioRandomIsOn.Name = "RadioRandomIsOn"
        RadioRandomIsOn.TabStop = True
        RadioRandomIsOn.Text = "Random assigned"
        RadioRandomIsOn.UseVisualStyleBackColor = True
        RadioRandomIsOn.Checked = True
        Me.Controls.Add(RadioRandomIsOn)

        RadioRandomIsOff.AutoSize = True
        RadioRandomIsOff.Location = New System.Drawing.Point(320, 32)
        RadioRandomIsOff.Size = New System.Drawing.Size(90, 17)
        RadioRandomIsOff.TabIndex = 2
        RadioRandomIsOff.Name = "RadioRandomIsOff"
        RadioRandomIsOff.TabStop = True
        RadioRandomIsOff.Text = "No random assigned"
        RadioRandomIsOff.UseVisualStyleBackColor = True
        Me.Controls.Add(RadioRandomIsOff)

        Dim tempLabel As Label = New Label()
        tempLabel.AutoSize = True
        tempLabel.Location = New System.Drawing.Point(317, 70)
        tempLabel.Name = "tempLabel"
        tempLabel.Size = New System.Drawing.Size(39, 13)
        tempLabel.TabIndex = 1
        tempLabel.Text = "total student per group"
        Me.Controls.Add(tempLabel)

        NumericUpDownTotalStudentPerGroup.Location = New System.Drawing.Point(320, 85)
        NumericUpDownTotalStudentPerGroup.Name = "NumericUpDownTotalStudentPerGroup"
        NumericUpDownTotalStudentPerGroup.Size = New System.Drawing.Size(90, 20)
        NumericUpDownTotalStudentPerGroup.TabIndex = 3
        Me.Controls.Add(NumericUpDownTotalStudentPerGroup)

        submitButton.Location = New System.Drawing.Point(320, 120)
        submitButton.Size = New System.Drawing.Size(80, 20)
        submitButton.Text = "Submit"
        Me.Controls.Add(submitButton)

        AddHandler RadioRandomIsOff.CheckedChanged, AddressOf Me.RadioButton_CheckedChanged
        AddHandler RadioRandomIsOn.CheckedChanged, AddressOf Me.RadioButton_CheckedChanged
        AddHandler NumericUpDownTotalStudentPerGroup.ValueChanged, AddressOf Me.NumericUpDown_ValueChanged
        AddHandler submitButton.Click, AddressOf Me.SubmitButton_Click

    End Sub  

    Private Sub RadioButton_CheckedChanged(ByVal sender As System.Object, ByVal e As System.EventArgs)
        If PassRunOnce Then
            myStudentOnGroup.IsRandom = RadioRandomIsOn.Checked
        End If
    End Sub

    Private Sub NumericUpDown_ValueChanged(ByVal sender As System.Object, ByVal e As System.EventArgs)
        If PassRunOnce Then
            myStudentOnGroup.StudentPerGroup = NumericUpDownTotalStudentPerGroup.Value
        End If
    End Sub

    Private Sub SubmitButton_Click(ByVal sender As System.Object, ByVal e As System.EventArgs)

        myStudentOnGroup.OnAssigned()
        DisplayBox.Items.Clear()
        Dim total As Integer = 1
        For i As Integer = 0 To myStudentOnGroup.TotalGroup - 1

            Dim subStudent() As String = myStudentOnGroup.GetStudentGroup(i)
            For j As Integer = 0 To subStudent.Length - 2 'Jagged array จะเติม สมาชิกมาให้อีกตัวเสมอ และมีค่าเป็น nothing ค่ะ
                Dim tempStr As String

                tempStr = total.ToString("000") + ")" _
                     + " กลุ่มที่ " + (i + 1).ToString("00") _
                     + " ลำดับที่ " + (j + 1).ToString("00") _
                     + " " + subStudent(j)
                DisplayBox.Items.Add(tempStr)

                total += 1
            Next

        Next
        DisplayBox.Refresh()
    End Sub
End Class
Public Class StudentAssignment
    Public TotalGroup As Integer = 0
    Public StudentPerGroup As Integer = 40
    Public OddStudentNumber As Integer = 0
    Public IsRandom As Boolean = False
    Public allStudent As List(Of String) = New List(Of String)
    Private _Student()() As String

    Public Sub New()

    End Sub

    Public Sub OnAssigned()

        Dim totalStudent As Integer = allStudent.Count
        Dim totalOddStudent As Integer = totalStudent Mod StudentPerGroup
        Dim tempAllStudent As List(Of String) = New List(Of String)

        'copy รายชื่อมาเพื่อจัดกลุ่ม
        tempAllStudent.AddRange(allStudent)

        TotalGroup = (totalStudent / StudentPerGroup)

        If (totalOddStudent) Then
            TotalGroup = TotalGroup + 1
        End If

        'Initial multidimention jaggged array
        _Student = New String(TotalGroup)() {}


        For i As Integer = 0 To TotalGroup - 1
            Dim totalStudentInGroup As Integer = StudentPerGroup
            If (totalOddStudent > 0) And (i = (TotalGroup - 1)) Then
                totalStudentInGroup = totalOddStudent
            End If
            Dim subStudent(totalStudentInGroup) As String

            Randomize()
            For j As Integer = 0 To totalStudentInGroup - 1

                Dim AssignedPosition As Integer
                If (Not IsRandom) Then
                    AssignedPosition = 0
                    'ถ้าไม่สุ่มก้อเลือกคนแรกในรายชื่อทั้งหมด เสมอ
                Else
                    'สุ่มลำดับมาจากรายชื่อทั้งหมด
                    AssignedPosition = CInt(Int(tempAllStudent.Count * Rnd()))
                End If

                subStudent(j) = tempAllStudent(AssignedPosition)
                tempAllStudent.RemoveAt(AssignedPosition)
                'ลบคนที่ถูกเลือกแล้วออกจากรายชื่อทั้งหมด
            Next
            _Student(i) = subStudent 'เพิ่มรายชื่อนักเรียนแต่ละกลุ่มเข้าไป
        Next

    End Sub

    Public Function GetStudentGroup(ByVal groupNumber) As String()
        If (groupNumber > TotalGroup - 1) Then
            Return Nothing
        Else
            Return _Student(groupNumber)
        End If

    End Function

End Class