想要制作缓存

Question

这是我遇到的问题的代码.这很简单,但我还在学习.我想缓存结果,因此函数返回比当前快几秒.此时它应该返回到4中的调用者,应该是2.

Sub Main
    console.writeline(getmyresult(2)) 'takes a while'
    console.writeline(getmyresult(3)) 'takes a while'
    console.writeline(getmyresult(2)) 'Should be instant'
    console.writeline(getMyresult(3)) 'Should be instant'
End Sub


function getMyresult(X as interger) as integer
    dim Y as integer=LongCompute(X)
    return Y
end function


function LongCompute(X as integer) as integer
    system.threading.thread.sleep(1000)
    return x^2
end function

任何帮助将不胜感激.

Answer 1

是的,这称为备忘录.

您可以在此处阅读:http: //en.wikipedia.org/wiki/Memoization

visual basic中的一个简单实现如下:

Dim dict As New Dictionary(Of Integer, Integer)

Sub Main()
    console.writeline(getmyresult(2)) 'takes a while'
    console.writeline(getmyresult(3)) 'takes a while'
    console.writeline(getmyresult(2)) 'Should be instant'
    console.writeline(getMyresult(3)) 'Should be instant'
End Sub

Function getMyresult(ByVal X As Integer) As Integer
    If dict.ContainsKey(X) Then
        Return dict(X)
    Else
        Dim temp = LongCompute(X)
        dict.Add(X, temp)
        Return temp
    End If
End Function

Function LongCompute(ByVal X As Integer) As Integer
    System.Threading.Thread.Sleep(1000)
    Return x ^ 2
End Function