Finding multiple combinations of sums in Excel - excel

Question

Ive been trying to make something in Excel to find multiple combinations of sums.
I have list of numbers that needs to be added together to be either within ranges of 500-510 or 450-460.
Only two numbers from the list can be used to find the sum. the numbers can not be used more than once. and giving the combinations of multiple results would be great. and if a number is not used it is ok.
I've tried the solver add-in and some other tips I found from this site but could not find something that gives multiple answers.
Does anyone know if this will be possible?

Answer 1

I'd break this into 2 tasks. First would be to simply generate all of the index pairs to test in the input array. That's relatively simple with recursive procedure. This one uses a private Type to store the pairs, but it could adapted to use some other method of storing the pairs:
Private Type Tuple
ValueOne As Long
ValueTwo As Long
End Type
Private Sub FindCombinations(elements As Long, ByRef results() As Tuple, _
Optional ByVal iteration As Long = 0)
If iteration = 0 Then ReDim results(0)
Dim idx As Long
For idx = iteration To elements - 1
Dim combo As Tuple
With combo
.ValueOne = iteration
.ValueTwo = idx
End With
results(UBound(results)) = combo
If iteration <> elements And idx <> elements Then
ReDim Preserve results(UBound(results) + 1)
End If
Next
If iteration < elements Then FindCombinations elements, results, iteration + 1
End Sub
Then, you use a "entry-point" procedure to generate the index combinations, use those to index into your source array, and apply your selection criteria:
Private Sub FindMatchingSets(testSet() As Long)
Dim indices() As Tuple
FindCombinations UBound(testSet) + 1, indices
Dim idx As Long, results() As Tuple
For idx = LBound(indices) To UBound(indices)
Dim tupleSum As Long
tupleSum = testSet(indices(idx).ValueOne) + testSet(indices(idx).ValueTwo)
If indices(idx).ValueOne <> indices(idx).ValueTwo And _
((tupleSum >= 500 And tupleSum <= 510) Or _
(tupleSum >= 450 And tupleSum <= 460)) Then
Debug.Print testSet(indices(idx).ValueOne) & " + " & _
testSet(indices(idx).ValueTwo) & " = " & tupleSum
End If
Next
End Sub
It isn't clear what you intend to do with the results, so this simply outputs the calculated values to the Immediate Window. Example calling code:
Private Sub Example()
Dim test(4) As Long
test(0) = 100
test(1) = 200
test(2) = 250
test(3) = 260
test(4) = 400
FindMatchingSets test
End Sub

Answer 2

May modify it according to your need & try
Sub test()
Dim X, Y, TRw, GotNum, First, Second As Long
TRw = 1
With ThisWorkbook.ActiveSheet
For X = 1 To 100 ' assumed col A1 to A100 is the list
GotNum = .Cells(X, 1).Value
If (GotNum >= 450 And GotNum <= 460) Or (GotNum >= 500 And GotNum <= 510) Then
.Cells(X, 1).Font.Color = RGB(255, 0, 0)
First = GotNum
For Y = X + 1 To 100
GotNum = .Cells(Y, 1).Value
If (GotNum >= 450 And GotNum <= 460) Or (GotNum >= 500 And GotNum <= 510) Then
Second = GotNum
TRw = TRw + 1
.Cells(TRw, 3).Value = First ' write 1st Number in Col C
.Cells(TRw, 4).Value = Second ' write 2nd Number in Col D
.Cells(TRw, 5).Value = First + Second ' write Sum of 1st & 2nd in Col C
End If
Next Y
End If
Next X
End With
End Sub

Answer 3

I think your question needs to be a little clearer in terms of what your expected output is (do you want a list of combos, or just to see the results?), but here's my solution.
I've put a list of 20 numbers in column Y, and assigned them all a letter (a through to t) in column X
Then I've built a matrix of the combinations of a to t, and have entered the following formula (the below is for cell C3, but it can be copied and pasted into all parts of the matrix)
=IF(C$2=$B3,"x",VLOOKUP(C$2,$X:$Y,2,FALSE)+VLOOKUP($B3,$X:$Y,2,FALSE))
I've then used conditional formatting to set the colour of the cells if they meet your criteria for the sum - you can do this by highlighting all the sums (cell C3:V22) and going to
home / conditional formatting / new rule...
picking the rule type format only cells that contain
and then in the drop down menus picking Cell Value / Between / Your high range
and then selecting a format (fill background colour, usually)
Do this once for the "high" sum, and once for the "low" sum. You can make the colours the same or different, depending on what you want to see.
I've also for reference included a reference to what the number is in Row 1 and column A. The formula for row 1 is (example is for C1, but it can be copied across)
=VLOOKUP(C2,$X:$Y,2,FALSE)
And the formula for column A is (example for A3) =VLOOKUP(B3,$X:$Y,2,FALSE)
The advantage of this approach is that it's all in excel (no code required), but the disadvantage is that it's hard to get a list of results. You could use a different formula to just return the sum (e.g. return the text "205+298") when it meets one of the conditions, but then it's still a pain to get it out of the matrix format and into a single list. Much easier using VBA