【加试题】小王设计了一个算法试图求出平面坐标系中最左点出发，从左往右途经所有点到达最右点的路径值和，编写了一个VB程序功能如下：在文本框Text1中输入需随机生成的坐标点数量，单击“生成”按钮Command1后，在列表框List1中生成相应数量的坐标点（坐标值为大于等于1小于10的实数 ，保留一位小数），在文本框Text2中输出路径值。程序界面如图所示。

实现上述功能的VB程序如下，但划线部分代码有错，请改正。

Private Sub Command1_Click()

  Dim x(1 To 100) As Single， y(1 To 100) As Single

  Dim tmp As Single， length As Single， sum As Single， x1 As Single， y1 As Single

  Dim i As Integer， j As Integer， k As Integer

Randomize 

List1.Clear

  k = Val(Text1.Text)

  For i = 1 To k

      x(i) = Int(Rnd * 90) / 10 + 1

      y(i) = Int(Rnd * 90) / 10 + 1

      List1.AddItem "X：" + Str(x(i)) + "   " + "Y：" + Str(y(i))

  Next i

  For i = 1 To k - 1

      For j = 1 To k - i

          If x(j) > x(j + 1) Then

              x(i)=x(i) + x(j)

              x(j) = x(i) - x(j)

              x(j) = x(i) + x(j)  ‘①

              tmp = y(j)

              y(j) = y(j + 1)

              y(j + 1) = tmp

          End If

      Next j

  Next i

  sum = 0： length = 0

  For i = 1 To k - 1

      x1 = (x(i) - x(1)) ^ 2    ‘②

 '变量y1计算方法同x1，代码略

      length = Sqr(x1 + y1)

      sum = sum + length

  Next i

  Text2.Text = Str(Int(sum * 10) / 10)

End Sub

① ②