学进去

试卷运送。五校联考就要到了，本次负责安排运送试卷的路线的是TBY。由于各所学校都参与了一些科目命题工作，所以目前每个学校里都有几个科目的试卷。为了节省运输费用，TBY想要找到一种能连接所有学校且线路总长最短的方案。
一共有n（3<=n<=100）个学校，各所学校之间的线路长度以一行共n*n个数据输入，
第i组的n个数据为从第i个学校出发到其他学校的线路长度，保证第i组的第i个数据为0。
编写VB程序，实现上述功能。运行程序，在文本框Text1中输入学校总数，
在文本框Text2中按题述方法输入各校之间的距离，点击命令按钮Command1后，在标签Label1中显示最短的线路总长。程序运行界面如图所示。

请回答下列问题：
（1）若n=4，各校距离为0242831240352528350303125300，则最短的线路总长为____________。
（2）实现上述功能的VB程序如下，请在划线处填入合适代码。
Const INF = 2147483646
Dim n As Long， a As Long
Dim dis(1 To 10001) As Long， flag(1 To 10001) As Boolean
Dim head(1 To 10001) As Long， nxt(1 To 10001) As Long
Dim ed(1 To 10001) As Long， value(1 To 10001) As Long
Dim cnt As Long， tby As Long， sss As String
Dim i As Long， j As Long
Private Sub Command1_Click()
       cnt = 0
       n = Val(Text1.Text)
       For i = 1 To n
             dis(i) = INF : flag(i) = False : head(i) = 0
       Next i
       tby = 1
       sss = Text2.Text
       For i = 1 To n
             For j = 1 To n
                    _______①        
                    If i <> j Then Call addedge(i， j， a)
             Next j
       Next i
       Dim ans As Long
       dis(1) = 0 : ans = 0
       For i = 1 To n
             Dim hg As Long， u As Long
             hg = INF
             u = 0
             For j = 1 To n
                    If ____________②             Then
                           hg = dis(j)
                           u = j
                    End If
             Next j
             _______③        
             flag(u) = True
             Dim p As Long
             p = head(u)
             Do While p <> 0
                    Dim v As Long
                    v = ed(p)
                    If Not flag(v) And dis(v) > value(p) Then
                           dis(v) = value(p)
                    End If
                    p = nxt(p)
             Loop
       Next i
       Label1.Caption = Str(ans)
End Sub
Sub addedge(a As Long， b As Long， x As Long)
       cnt = cnt + 1
       value(cnt) = x
       ed(cnt) = b
       nxt(cnt) = head(a)
       head(a) = cnt
End Sub
Function Getin() As Long
       Dim aaa As String
       aaa = Mid(sss， tby， 1)
       If aaa = " " Then tby = tby + 1
       aaa = Mid(sss， tby， 1)
       Dim bbb As Long
       bbb = 0
       Do While aaa <> " " And tby <= Len(sss)
             bbb = bbb * 10 + Val(aaa) : tby = tby + 1
             aaa = Mid(sss， tby， 1)
       Loop
       Getin = bbb
End Function