excel - VBA 最长 Collat​​z 序列

Question

我正在编写一个 Sub 来识别 1 到 1000 之间最长的 Collat​​zs 序列。由于我刚刚开始学习 VBA，我想知道如何添加过程来计算每个序列的长度。

Sub Collatz()

Dim i As Long
Dim maxSteps As Integer


    For i = 1 To 1000
    
        If i = 1 Then
            maxSteps = CInt(20.856 * Log(2))
        Else
            maxSteps = CInt(20.856 * Log(i))
        End If
    
        If i Mod 2 = 0 Then
            i = i / 2
        Else
            i = 3 * i + 1
        End If
    
    Debug.Print i
    
    Next i
    
End Sub

Answer 1

我不确定 Log 在你的示例中应该做什么，但我会这样写:

Sub Collatz()
    Dim i As Long, j As Long
    Dim steps As Long
    Dim n As Long
    Dim maxSteps As Long

    For i = 1 To 1000
        j = i
        steps = 1
        Do Until j = 1
            If j Mod 2 = 0 Then
                j = j / 2
            Else
                j = 3 * j + 1
            End If
            steps = steps + 1
        Loop
        If steps > maxSteps Then
            n = i
            maxSteps = steps
        End If
    Next i
    Debug.Print n, maxSteps
End Sub