超级难题，高手进来挑战挑战看！50分哟！！！！！！！！！！
实现如下功能：
当传入参数string a = "1 ";时

for (int i = 0; i < a.Length; i++)
sum += i;
当传入参数string a = "12 ";时

for (int i = 0; j < a.Length; i++)
for (int j = 0; j < i; j++)
sum += （i + j);

当传入参数string a = "123 ";
for (int i = 0; j < a.Length; i++)
for (int j = 0; j < i; j++)
for (int k = 0; k < j; k++)
sum += (i + j + k);

假设string a = "123456... "

依次类推...

设计一个方法：
static int fun(string a)
{
int sum = 0;
//在此写代码
return sum;
}

求解注释位置的代码:)

[解决办法]
0> 1> 2> 3> 4....> a.Length-1,满足条件的只有一种情况，就是0+1+2+3+...+a.Length-1
[解决办法]
Sub DoIt(ByRef Sum As Integer, ByVal StrCode As String, ByVal CurLength As Integer, ByVal TempSum As Integer, ByVal Cyc As Integer)
Dim II As Integer
For II = 0 To CurLength - 1
If Cyc = StrCode.Length Then
Sum = TempSum + II
Else
Cyc += 1
TempSum += II
DoIt(Sum, StrCode, II, TempSum, Cyc)
End If
Next
End Sub

Function GetSum(ByVal StrCode As String) As Integer
Dim Sum As Integer
DoIt(Sum, StrCode, StrCode.Length, 0, 1)
Return Sum
End Function

Private Sub MyButton1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyButton1.Click
MsgBox(GetSum( "abcd "))
End Sub

不知道是否正确哈~~简单的写了一下，思路没问题，但是可能算法不够简练；
第归应该还是可以实现的，回头转换成C#给你，我不大会C#，可能会有问题