学进去

将n个元素转换成(n\m)*m矩阵（n是m的倍数）。例如有42个元素，m=7，则可转换成6*7（6行7列）的矩阵转换示例如下：
转换前元素次序为：
12 2 5 3 6 9 4 10 8 5 6 9 6 3 5 8 11 2 8 9
转换为矩阵如下：
   
现要在矩阵中找一个规模为3*3的子方阵，使得该子方阵的各元素之和最大。
（1）若n=25，m=5，则该矩阵中共有3*3的子方阵个数为________。（填数字）
（2）实现上述功能的VB程序如下，请在划线处填入合适代码。
Private Sub Command1_Click()
Dim a(1 To 100) As Integer
Dim sum(0 To 101) As Long ’sum(i)=a(1)+a(2)+a(3)+…+a(i)
Dim i As Integer, j As Integer, n As Integer, m As Integer, k As Integer
Dim ans As Long, begin As Integer, maxi As Integer
Dim maxsum As Long, s As String
n=Val(Text1.Text)
m=Val(Text2.Text)
If n Mod m <> 0 Then List1.AddItem “输入数据不符合要求”:Exit Sub
For i=1 To n
a(i)=Int(Rnd*50+1)
s=s+Str(a(i))
If i Mod m=0 Then List1.AddItem s:s=“”
Next i
k=3
sum(1)=a(1)
For i=2 To n  ’求sum(i)
_______
Next i
maxsum=0
ans=0
For i=1 To n\m-k+1
For j=k To m
begin=(i-1)*m+j-k+1
maxsum=maxsum+sum(j+(i-1)*m)-sum(j-k+(i-1)*m)
________
maxsum=maxsum+(j+(i+1)*m)-sum(j-k+(i+1)*m)
If maxsum>ans Then ans=maxsum:maxi=begin
maxsum=0
Next j
Next i
s= “”
For i=1 To k
For j=1 To k
s=s+Str(a (（________）))
Next j

List2.AddItem s

s=“”

Next i
List2.AddItem “maxsum=”+Str(ans)
End Sub