以下程序的功能是验证"数学黑洞6174"。对于任意一个各位数字不全部相同的四位整数,将组成该数的数字组合成一个最大的数和一个最小的数,二者相减,判断其差值是否为6174,若不是,再将相减的结果组合成新的最大的数和最小的数,以上过程最多重复7次,必得结果6174。程序运行界面如图所示。 Option Explicit Option Base 1 Private Sub Cmd1_Click()Dim i As Integer,k As IntegerDim max As Integer min As Integerk=Val(Text1)For i=1 T0 3 ’判断4位数字是否全部一样 If Mid(CStr(k),i,1)<>Mid(CStr(k),i+1,1) Then ___(26)___Next iIf i>3 Then MsgBox "输入的数据不合要求" Text1="" Exit SubEnd IfFor i=1 To 7 Call Validate(k max,min) List1.AddItcm k &":" & max &"-" & min & "=" & max-min If max-min=6174 Then Exit For Else k=___(27)___ End IfNext iIf ___(28)___ Then List1.AddItem "验证失败!" End Sub Private Sub Validate(n As Integer,max As Integer,min As Integer)Dim i As Integer,t(4)As IntegerDim s As String,s1 As String,s2 As StringS=CStr(n)For i=1 To 4 t(i)=Val(Mid(s,i,1))Next iCall sort(t)For i=1 To 4 s1=s1 & CStr(t(i)) s2=___(29)___Next imin=Val(s1)max=VaI(s2) End Sub Private Sub sort(a() As Integer)Dim i As Integer,j As Integer,t As IntegerFor i=1 To UBound(a)-1 For j=i+1 To UBound(a)If ___(30)___ Then t=a(i):a(i)=a(j):a(j)=tEnd If Next jNext i End Sub
