题目

【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  答案：【1】x(i)=x(i)–x(j)【2】(x(i)–x(i+1))^2或其他等价表达式

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