vb.net 计算组合

? Private Function compute(ByVal n As Long, ByVal r As Long)
??????? Dim result As Decimal = 1
??????? Dim temp1 As Decimal = 1
??????? Dim temp2 As Decimal = 1
??????? If r = 0 Then
??????????? result = 1
??????? Else
??????????? 'n(n-1).....(n-r+1)
??????????? For i As Long = n To n - r + 1 Step -1
??????????????? temp1 *= i
??????????? Next
??????????? 'r!
??????????? For i As Long = r To 1 Step -1
??????????????? temp2 *= i
??????????? Next
??????????? result = temp1 / temp2
??????? End If
??????? Return result
??? End Function