Excel VBA中的组合algorithm
我需要一个algorithm来生成所有可能的组合号码，并将它们全部输出到Excel电子表格中。
例如，n = 5（1,2,3,4,5）和r = 2（为此创build一个小的gui），它将生成所有可能的组合，并将其输出到excel电子表格中，如下所示。
1,2 1,3 1,4 ... 它的打印顺序无关紧要。 它可以首先打印（5,1），然后（1,2）。 任何人都可以告诉我如何做到这一点？
非常感谢你。
这个代码如何…
Option Explicit Private c As Integer Sub test_print_nCr() print_nCr 5, 3, Range("A1") End Sub Function print_nCr(n As Integer, r As Integer, p As Range) c = 1 internal_print_nCr n, r, p, 1, 1 End Function Private Function internal_print_nCr(n As Integer, r As Integer, ByVal p As Range, Optional i As Integer, Optional l As Integer) As Integer ' n is the number of items we are choosing from ' r is the number of items to choose ' p is the upper corner of the output range ' i is the minimum item we are allowed to pick ' l is how many levels we are in to the choosing ' c is the complete set we are working on If n < 1 Or r > n Or r < 0 Then Err.Raise 1 If i < 1 Then i = 1 If l < 1 Then l = 1 If c < 1 Then c = 1 If r = 0 then p = 1 Exit Function End If Dim x As Integer Dim y As Integer For x = i To n - r + 1 If r = 1 Then If c > 1 Then For y = 0 To l - 2 If p.Offset(c - 1, y) = "" Then p.Offset(c - 1, y) = p.Offset(c - 2, y) Next End If p.Offset(c - 1, l - 1) = x c = c + 1 Else p.Offset(c - 1, l - 1) = x internal_print_nCr n, r - 1, p, x + 1, l + 1 End If Next End Function
我不得不这样做一次，并最终适应这个algorithm 。 它与嵌套循环有些不同，所以你可能会觉得很有趣。 转换为VB，这将是这样的：
Public Sub printCombinations(ByRef pool() As Integer, ByVal r As Integer) Dim n As Integer n = UBound(pool) - LBound(pool) + 1 ' Please do add error handling for when r>n Dim idx() As Integer ReDim idx(1 To r) For i = 1 To r idx(i) = i Next i Do 'Write current combination For j = 1 To r Debug.Print pool(idx(j)); 'or whatever you want to do with the numbers Next j Debug.Print ' Locate last non-max index i = r While (idx(i) = n - r + i) i = i - 1 If i = 0 Then 'All indexes have reached their max, so we're done Exit Sub End If Wend 'Increase it and populate the following indexes accordingly idx(i) = idx(i) + 1 For j = i + 1 To r idx(j) = idx(i) + j - i Next j Loop End Sub