Library tutorials & articles
Bin Packing
By Mitch Dusina, published on 31 Mar 2006
First Fit Algorithm
Now let's talk about an algorithm with a little more "intelligence". The
First Fit Algorithm
does exactly as its name implies. It steps through the Elements
sticking them into the first Bin it can, if there aren't any Bins that
it will fit into, a new Bin is added. You will get pretty
efficient use of Bins with this algorithm.
With the same set of data as the last example, this algorithm will lay out something like this in memory:
Private Sub FirstFit()
'Checks to make sure everything is initialized
If Elements Is Nothing Then Exit Sub
Dim ElementsCopy(Elements.GetUpperBound(0)) As Integer
ReDim Bins(0)
'Bin Number we are on, Bin Element we are on, Amount placed in the current Bin
Dim BinNumber, BinElement, BinCount As Integer
Dim i, j, k As Integer
'Make a copy of the array incase we need to sort it
DeepCopyArray(Elements, ElementsCopy)
'Sort in descending order if needed
If Me.Decreasing = True Then
Array.Sort(ElementsCopy)
Array.Reverse(ElementsCopy)
End If
'Declare the first element in the first Bin
ReDim Bins(0)(0)
'Loop through each Element and place in a Bin
For i = 0 To ElementsCopy.GetUpperBound(0)
Dim bPlaced As Boolean = False
'Loops through each Bin to find the first available spot
For j = 0 To BinNumber
BinElement = Bins(j).GetUpperBound(0)
'Count the amount placed in this Bin
BinCount = 0
For k = 0 To BinElement
BinCount += Bins(j)(k)
Next
If BinCount + ElementsCopy(i) <= Me.BinHeight Then
'There's room for this Element
ReDim Preserve Bins(j)(BinElement + 1)
Bins(j)(BinElement) = ElementsCopy(i)
bPlaced = True
Exit For
Else
'There's not room for this Element in this Bin
End If
Next
'There wasn't room for the Element in any existing Bin
'Create a new Bin
If bPlaced = False Then
'Add another Bin
ReDim Preserve Bins(BinNumber + 1)
BinNumber += 1
'Initialize first element of new bin
ReDim Bins(BinNumber)(1)
BinElement = 0
Bins(BinNumber)(BinElement) = ElementsCopy(i)
End If
Next
'All Elements have been place, now we go back and remove unused Elements
For i = 0 To BinNumber
For j = 0 To Bins(i).GetUpperBound(0)
If Bins(i)(j) = 0 Then
ReDim Preserve Bins(i)(j - 1)
End If
Next
Next
GC.Collect()
End Sub
With the same set of data as the last example, this algorithm will lay out something like this in memory:
Languages I know (from most comfortable with, to least comfortable with): VB.NET, C#, VB6, and C/C++
I'm 19 years old and pursuing a MS in Computer Science at the Colorado School of Mines. M...
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keen to have a look the c++ code.
zxy901109@hotmail.com
cheers
Hi Nimpo
thank you for this fine sourcecode, it helps me in understanding the problem of bin packing a bit, a porblem i just want to solve in my access database
but i have a question and something i did not found in your programm.
you mentioned the possibility of bins with different heights, but i did not find this in the sourcecode or how to enter it
and anothe question, do you think that your solution will work in combination with an existing access database ?
thanks
Andreas
Hello,
I really want to thank you for for this great article. However, I am currently working on my last year project, which is about 2 dimensional sheet cutting optimizer. Unfortunalty, I did not find any article that explains how to implement it by code.
Please can any one help me, this is very important because I just have about 2 weeks to finish it.
If any one has some helpful resources please send it to my email mishoco@hotmail.com
Michel
Hi,
i urgently need the codes too before 19/09/07. pls help me. could you send me the C++ and java version of the codes. Tankyou. send to nuranastacia@yahoo.com
can u plz send me a 'C++' or 'C' program code for first fit algorithms....
i need it urgently.... i need to submit code as my project by saturday 09/15/07...
example output:
enter no. of process to be loaded: 4
Job # Job size Arrival time
1 40K 0 msec
2 15K 7 msec
3 10K 5 msec
4 45K 10 msec
press any key to continue...
note: Job size and Arrival time will be inputted by the user and as you press enter in the Job size, "K" will be automatically displayed as well as the "msec" in the arrival time.
I believe that the First Fit algorithm will always be better than or equivalent to the Next Fit algorithm.
I first learned of the Bin Packing problem from an Algebra 3 class in high school. I implemented all of the algorithms the textbook talked about. Doing some quick online research, the only other algorithm I found a mention of was the "Almost Worse Fit". It simply places the object in the second emptiest bin (which is slightly better than Worse Fit apparently).
I cannot myself convert my code into other languages (I do not have the time or the motivation). But the concepts used in my code are not very language specific. It shouldn't take much time to do the conversion. If you do not know the target language well then you will simply have to search online for the syntax for that particular structure (Arrays, sorting, and drawing is all there really is to it, and I would think that drawing isn't that important). Plus, that way you'd actually be learning the language you are supposed to learn =)
i am in the same situation can u plz send me a C or C++ code for best/first/worst fit algorithms....
i need it to complete my assignment
bion365@gmail.com
thanks
can u plz send me a 'C' program code for best/first/worst fit algorithms....
i need it urgently.... i need to submit code as assignment......PLZ HELP
rrookwood_jm@yahoo.com
hey... grt job buddy...
can u plz send me a 'C' program code for best/first/worst fit algorithms....
i need it urgently.... i need to submit code as assignment..... by sunday...
plz help....
ritusmart2001@yahoo.com
Hello,
I'm new here and maybe missing something. Everybody says 'Great article' - but where the article itself? Same for code - is there code example or algorithm available?
Thanks.
Have you provided all the algorithms that are available to solve Bin Packing ?
I would also like to see a solution for the 0-1 Knapsack problem where each article(File) have a weight(MB) as well as a value(priority). The sack capacity let's say 700MB.
Thank you.
Great article. Thanks.
Hi,
Excellent article. Would you know how or have a PHP version of this problem?
Regards, Michael
I have a quick question. Can there ever be more bins in a First Fit Algorithm than a Next Fit algorithm?
Well as for variable sized bins, all you would need to do is have an array of Integers that holds the size for each Bin. Then in my code, where ever there is a reference to BinHeight, you would simply reference BinHeightArray(ThisBinNumber) instead. You could incorporate all this code into its own Class as it should be an make the array a property so you can do bounds checking, check for valid values, and all that good stuff.
As for 2-dimensional Bin Packing... I'd have to get back to you on that one. I understand what you mean but I don't think these algorithms are easily translatable into another dimension... Try to formulate an algorithm that starts filling in the lower left to the lower right, and then starts moving up. I can't vouch for the efficiency of this idea but its my only lead...
Great article, I was looking for something exactly like this! How difficult would it be to modify the code to allow for varible size bin widths, and then pack each element either horizontal or vertial depending on height and width. If you can figure that out let me know. Thanks and keep up the good work.![Smiley Face [:)]](/emoticons/emotion-1a.gif)
This thread is for discussions of Bin Packing.