VBA -将数字的所有排列写入数组

Option Explicit

Sub Permutations()
    Dim inputArray() As Variant
    Dim outputArray() As Variant
    Dim resultArray() As Variant
    Dim currentIndex As Integer
    Dim i As Integer
    
    ' 输入数字数组
    inputArray = Array(1, 2, 3)
    
    ' 初始化输出数组
    ReDim outputArray(UBound(inputArray))
    
    ' 调用递归函数获取所有排列
    Permute inputArray, outputArray, 0
    
    ' 输出结果
    For i = 0 To UBound(resultArray)
        Debug.Print Join(resultArray(i), ", ")
    Next i
End Sub

Sub Permute(inputArray() As Variant, outputArray() As Variant, currentIndex As Integer)
    Dim i As Integer
    
    ' 如果当前索引等于输入数组的长度，则将当前排列添加到结果数组中
    If currentIndex = UBound(inputArray) Then
        resultArray = AppendArray(resultArray, outputArray)
        Exit Sub
    End If
    
    ' 递归调用，将每个数字放在当前位置，并继续处理下一个位置
    For i = 0 To UBound(inputArray)
        If Not IsInArray(inputArray(i), outputArray) Then
            outputArray(currentIndex) = inputArray(i)
            Permute inputArray, outputArray, currentIndex + 1
        End If
    Next i
End Sub

Function AppendArray(arr1() As Variant, arr2() As Variant) As Variant()
    Dim i As Integer
    Dim j As Integer
    Dim k As Integer
    
    ' 初始化结果数组
    ReDim resultArray(0 To UBound(arr1) + 1)
    
    ' 复制arr1到resultArray
    For i = 0 To UBound(arr1)
        resultArray(i) = arr1(i)
    Next i
    
    ' 复制arr2到resultArray
    For j = 0 To UBound(arr2)
        resultArray(i + j) = arr2(j)
    Next j
    
    ' 返回结果数组
    AppendArray = resultArray
End Function

Function IsInArray(value As Variant, arr() As Variant) As Boolean
    Dim i As Integer
    
    ' 遍历数组，查找是否存在指定值
    For i = 0 To UBound(arr)
        If arr(i) = value Then
            IsInArray = True
            Exit Function
        End If
    Next i
    
    ' 没有找到指定值
    IsInArray = False
End Function