Algorithm help.

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October 29th, 2012, 09:09 PM

huyvu90

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Algorithm help.

Let say I have an array with the following numbers:

1,4,12,22,53,51,49,55,2,5,50,51,100

I'm trying to develop an algorithm that finds the max number of consecutive number in the array that is between 40 and 60.

For the example above, the algorithm should return 53,51,49 and 55. 50,51 are not returned because that is only 2 consective number that is between 40 and 60.

November 25th, 2012, 10:01 PM

argee

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Hi huyvu90,

Unless I'm misunderstanding, I think this should do what you want:

Code:

Dim ArNums() As Integer
Dim i As Integer, j As Integer
Dim savej As Integer

'....code to load numbers into array ArNums
    
     For i = 0 To UBound(ArNums)
        If ArNums(i) > 40 And ArNums(i) < 60 Then
            j = j + 1
            If j > savej Then
                savej = j
            End If
        Else
            j = 0
        End If
    Next i

    MsgBox savej          '<----- this should be your answer
                                ' ('4' for your example)

cheers,

argee

January 1st, 2013, 04:09 AM

Incidentals

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Quote:

Originally Posted by argee

Hi huyvu90,

Unless I'm misunderstanding, I think this should do what you want:

Code:

Dim ArNums() As Integer
Dim i As Integer, j As Integer
Dim savej As Integer

'....code to load numbers into array ArNums
    
     For i = 0 To UBound(ArNums)
        If ArNums(i) > 40 And ArNums(i) < 60 Then
            j = j + 1
            If j > savej Then
                savej = j
            End If
        Else
            j = 0
        End If
    Next i

    MsgBox savej          '<----- this should be your answer
                                ' ('4' for your example)

cheers,

argee

you missed the point!

you have coded for an algorythm that returns the number of 40 to 60 values and not considered the consecutive part of the question

the looping is fine but you need to be looking ahead and you need to be flagging the count-now nature of the problem

try walking through the array with 2 pointers if and only if they both point to values in the range should you show them and remember to indicate that a match has ben found. Using the match you will be able to deduce that the first pointer is pointing at a valid entry when the pointers no longer have values in range and at that point you should reset the flag and output the first pointed to value.

hope that explains what to do

code available if needed

January 1st, 2013, 12:30 PM

argee

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I am allowing for the consecutive part of the problem.

That's why the loop resets the value of j to 0 if a match is not found, because then the matches are no longer consecutive.

The number of consecutive matches is stored in "savej" only if it exceeds any previously stored value in "savej".

I had considered afterwards that, although they initially said they wanted the maximum number of values, the OP may have wanted the actual consecutive number group returned, not just the count of them. The code could be modified like this :

Code:

Dim intStartPos As Integer
Dim strResult As String

'...code to load numbers into array ArNums
    
    For i = 0 To UBound(ArNums)
        If ArNums(i) > 40 And ArNums(i) < 60 Then
            j = j + 1
            If j > savej Then
                savej = j
                intStartPos = i - j
            End If
        Else
            j = 0
        End If
    Next i

    For i = (intStartPos + 1) To (intStartPos + savej)
        strResult = strResult & ArNums(i) & ","
    Next i

    Debug.Print strResult       'contains the consecutive matches separated by commas

In any case, this thread is aging and the original poster has not returned it seems.

January 1st, 2013, 04:51 PM

Incidentals

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nicely done

I didnt complete my writeup, but its nice to see you did - well done, and the explaination will help others understand your process better.

February 9th, 2013, 04:36 PM

GGriggs

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algorythm

the main power of VBA is to use it with excel to do the serious number crunching

Your problem is quite hard in vba but very easy in excel

use VBA to load input and extract and display answers and excel to crunch the numbers

i can't attach for some reason but i have written a spreadsheet to crack it in about 2 mins

email me at graham.griggs@tiscali.co.uk and i will send you a copy

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