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--  作者：keli0917
--  发布时间：2023/9/6 21:10:00
--  凑数
假设有一组数1，2，5，9，1，0，4，5，从中选N个数，凑成10。
例出所有的分组。
帮忙完善一下，递归真的不懂。

\'递归函数,用于数组中寻找N项之和等于目标值的组合
Dim str As String = args(0) \'原始数组
Dim nums() As String = str.Split(",") \'将str内容拆分成数组
Array.Sort(nums)
Dim target As Decimal=args(1) \'目标值
Dim n As Integer= args(2) \'N项,N张发票号码
Dim StartIndex As Integer = args(3) \'一般为0

Dim sum As Decimal
Dim result() As Decimal
\'当n=2时,转为寻找两项之和等于目标值的问题
If n = 2 Then
Dim left As Integer = StartIndex \'左指针从STRARTINDEX开始
Dim right As Integer = nums.length - 1
\'使用双指针法搜索满足条件的组合
Do While left < right
sum = val(nums(left)) + val(nums(right))
\'MessageBox.Show(nums(left))
\'MessageBox.Show(nums(right))
\' MessageBox.Show("sum:="&sum)
\' MessageBox.Show("target:="&target)
If sum = target Then
result = New Decimal() {nums(left),nums(right)}\'找到一组解,加入结果数组
messagebox.Show(result(0))
messagebox.Show(result(1))

left = left +1
right = right - 1
\'跳过重复的元数
Do While left < right And nums(left) = nums(left - 1)
left = left +1
Loop
Do While left < right And nums(right) = nums(right + 1)
right = right - 1
Loop
\'跳过重复的元数 end
ElseIf sum < target Then
left = left +1
Else
right = right -1

End If
Loop
Else
\'当N不等于2时,使用递归寻找N-1项之和等于targe 减去当前项的组合
Dim i As Integer
For i = startindex To nums.length - n + 1
If i = startindex Or nums(i) <> nums(i-1) Then
Functions.Execute("N个数和等于M",nums,target - nums(i),n-1,i+1)
End If
Next
End If

--  作者：有点蓝
--  发布时间：2023/9/7 13:08:00
--
函数，假设名称为child

Dim ss() As Integer = Args(0) \'原数组
Dim target As Integer = Args(1) \'结果和
Dim currentSum As Integer = Args(2) \'累加和
Dim idx As Integer = Args(3) \'开始索引
Dim n As Integer = Args(4) \'遍历层次。或者叫做取数个数，比如任意取2个数字的和为10，表示n是2;任意取3个数字的和为10，表示n是3
Dim lst As List(Of Integer) = Args(5) \'参与计算的数组集合
Dim res As List(Of List(Of Integer)) = Args(6) \'结果
If n = 1 Then \'表示是已经取的最后一个数字
For i As Integer = idx + 1 To ss.Length - 1 \'遍历最后一个数字
If currentSum + ss(i) = target Then \'如果和之前的数字累加为10
Dim lst3 As New List(Of Integer)
lst3.AddRange(lst)
lst3.Add(ss(i))
res.Add(lst3) \'添加到结果中
End If
Next
Else \'还不是最后一个数字
For i As Integer = idx + 1 To ss.Length - 1
Dim lst2 As New List(Of Integer) \'新增一个集合，避免重复添加
lst2.AddRange(lst) \'添加之前的数字
lst2.Add(ss(i)) \'添加新的数字
Functions.Execute("child", ss, target, currentSum + ss(i), i, n - 1, lst2, res) ‘继续计算下一层数字
Next
End If

调用
Dim ss As Integer() = {1, 2, 5, 9, 1, 0, 4, 5}
Dim target As Integer = 10
Dim res As New List(Of List(Of Integer))
Dim lst As List(Of Integer)
For n As Integer = 2 To ss.Length - 1
lst = New List(Of Integer)
Functions.Execute("child", ss, target, 0, - 1, n, lst, res)
Next

\'显示结果
For Each re As List(Of Integer) In res
Output.Show(String.Join(", ", re))
Next

[此贴子已经被作者于2024/9/29 10:10:32编辑过]

--  作者：keli0917
--  发布时间：2024/9/28 21:51:00
--
Dim ss As Integer() = {1, 9, 9}
Dim ss As Integer() = {1, 9, 9，9}
————————
当SS为上面的组合时，上面函数会出错，可以帮忙修改一下吗

[此贴子已经被作者于2024/9/28 21:54:33编辑过]

--  作者：有点蓝
--  发布时间：2024/9/29 10:10:00
--
函数改为

Dim ss() As Integer = Args(0) \'原数组
Dim target As Integer = Args(1) \'结果和
Dim currentSum As Integer = Args(2) \'累加和
Dim idx As Integer = Args(3) \'开始索引
Dim n As Integer = Args(4) \'遍历层次。或者叫做取数个数，比如任意取2个数字的和为10，表示n是2;任意取3个数字的和为10，表示n是3
Dim lst As List(Of Integer) = Args(5) \'参与计算的数组集合
Dim res As List(Of List(Of Integer)) = Args(6) \'结果
\'Dim f As String = Date.Now.ToString("mm:ss.ffff")
\'Output.Show("idx=" & idx & ",n=" & n & ",currentSum=" & currentSum & ",------: " & f)
If n = 1 Then \'表示是已经取的最后一个数字
For i As Integer = idx + 1 To ss.Length - 1 \'遍历最后一个数字
If currentSum + ss(i) = target Then \'如果和之前的数字累加为10
Dim lst3 As New List(Of Integer)
lst3.AddRange(lst)
lst3.Add(ss(i))
res.Add(lst3) \'添加到结果中
End If
Next
Else \'还不是最后一个数字
\' Output.Show("lst.Count=" & lst.Count)
For i As Integer = idx + 1 To ss.Length - 1
Dim lst2 As New List(Of Integer) \'新增一个集合，避免重复添加
lst2.AddRange(lst) \'添加之前的数字
lst2.Add(ss(i)) \'添加新的数字
Functions.Execute("child", ss, target, currentSum + ss(i), i, n - 1, lst2, res) \'继续计算下一层数字
Next
End If
\'Output.Show("------end: " & f)