主题：[讨论]用洗牌法抽取记录的例子是否有问题？

在帮助的开发指南 》 Foxtable编程 》 杂谈 》高效随机抽取记录 中用洗牌法抽取记录的程序如下 

Dim cnt As Integer = DataTables("订单").DataRows.Count
Dim ids1 As New List(of Integer) '用于存储洗牌前的位置
Dim ids2 As New List(of Integer) '用于存储洗牌后的位置
For i As Integer = 0 To cnt -1 '准备初始的牌
    ids1.add(i)
Next
For i As Integer = 0 To cnt - 1 '开始洗牌
    ids2.Add(ids1(rand.Next(0,ids1.count)))
Next
Tables("订单").StopRedraw()
DataTables("订单").ReplaceFor("选择",False)
For i As Integer = 0 To 100 - 1 '100为要抽取的行数
    DataTables("订单").DataRows(ids2(i))("选择") = True
Next
Tables("订单").Filter = "[选择] = True"
Tables("订单").ResumeRedraw()

我测试其中开始洗牌的程序有点问题，ids2中可能会有重复值

For i As Integer = 0 To cnt - 1 '开始洗牌
    ids2.Add(ids1(rand.Next(0,ids1.count)))
Next

麻烦老师看看有问题么

帮助文档这样写，有问题，洗牌，不是这样洗的。

Dim dt As DataTable = DataTables("表A")
Dim cnt As Integer = dt.DataRows.Count
Dim ids(cnt - 1) As Integer
For i As Integer = 0 To cnt -1
    ids(i) = i
Next
For i As Integer = 0 To cnt \ 2 '洗牌次数
    Dim id1 As Integer = rand.Next(0,cnt)
    Dim id2 As Integer = rand.Next(0,cnt)
    Dim vid As Integer = ids(id1)
    ids(id1) = ids(id2)
    ids(id2) = vid
Next
dt.StopRedraw()
For i As Integer = 0 To ids.length -1
    output.show(ids(i))
Next
dt.ResumeRedraw()