The Big Programming Thread - Page 825

On January 07 2017 02:44 spinesheath wrote:
First of all you should sort your lines by length. There should be a sort-method readily available in Java, you might have to pass it a Comparer of sorts, which converts a line into its length. The result of this step is a sorted list of lines.

Then in the second step, you iterate over the sorted lines. For each line, you check it against all lines, which you do again by iterating over the sorted lines, skipping the one you're currently checking. If you find one that doesn't intersect any line, you return that one as a result. It is the smallest one because it's the first in the sorted list.

There is no recursion here. It's a naive approach, but clean and simple. It's O(n^2). More sophisticated approaches probably would keep the first part, but tweak the second part to use sort of a divide and conquer approach, but that won't be very simple at all. I can imagine O(n log n), but I don't know if it actually is possible.

This approach includes a number of pointless checks, in the worst case 50%. This is because I check against all lines without skipping the pairs already covered. We can avoid that easily by storing the sorted lines in a list, then iterate over the list by index. If we are currently at list[5], we only check against list[6] and beyond:

for(int i = 0; i < list.Count; ++i) {
  for(int k = i + 1; k < list.Count; ++k) {
    check if list[i] intersects list[k];
  }
}

Still is O(n^2) though.

Always ask yourself if you can split your problem into smaller chunks. Sort first, check after. Simple approach first, optimization after.

Also Java or rather the JVM is not well equipped for heavy recursion. Don't avoid recursion at all costs, but if you're doing a lot of work with deep recursion, you probably should try to avoid it.

On January 07 2017 06:25 travis wrote:
Okay I've got a question for the professionals out there

on my resume, what sort of terminology should I use to explain how familiar I am with languages/systems?

For example, I've been programming almost exclusively in Java, have finished 2 rigorous classes on it, and feel like with just a small amount of research I could do most of what there is to do in Java. But there's still lots to learn, of course.
Would it be reasonable to say that I am "fluent in java" on my resume?

Let's say I finish a large introductory text on python and learn all the concepts, and I am now capable of writing basic python programs. could I say that I am "familiar" with python?

etc etc

thanks



also, I am filling out an online application for an internship and they ask me "are you familiar with high and low level languages". I feel like the answer is obviously "no" since I don't know any low level languages. I do, however, have a basic idea of how assembly works.. But they are wanting me to actually know how to program in assembly / something comparable?

On January 07 2017 23:09 Djagulingu wrote:

You might rate yourself on your skills on a scale of 1 to either 3, 5 or 10. Also, nobody wants you to know how to program in assembly. I know how to do it and never had to use it for anything professionally. I don't rate my skills in my resume. They are just a comma separated list. I don't even think that people take this stuff seriously.

What matters most is always projects. If you feel like with just a small amount of research I could do most of what there is to do in Java, do something with it. Not just say you're "fluent in java" or whatever the bull crap that is. You're going to be a fresh grad. Projects will be a yes/no question for you, not a "wh-" question (unlike more senior developers). If you have something to show, you're golden.

Also, Low level languages are C and C++. I don't even think your recruiter/boss/manager can program in assembly, even if s/he is a "lead/staff/senior embedded systems developer". They only teach assembly to students so that they have a better idea about what happens under the hood.

On January 08 2017 00:52 RoomOfMush wrote:

There are a few select positions where you need to use assembly though. Highly unlikely travis will end up with one of these but perfectly possible. I wouldnt recommend learning it though unless out of curiousity. If you really need it for your job it will probably be something very specific which you will need to learn again anyways.

On January 08 2017 04:48 travis wrote:


Am I right in guessing that you need it for reverse engineering?

On January 07 2017 06:25 travis wrote:
Okay I've got a question for the professionals out there

on my resume, what sort of terminology should I use to explain how familiar I am with languages/systems?

For example, I've been programming almost exclusively in Java, have finished 2 rigorous classes on it, and feel like with just a small amount of research I could do most of what there is to do in Java. But there's still lots to learn, of course.
Would it be reasonable to say that I am "fluent in java" on my resume?

Let's say I finish a large introductory text on python and learn all the concepts, and I am now capable of writing basic python programs. could I say that I am "familiar" with python?

etc etc

thanks



also, I am filling out an online application for an internship and they ask me "are you familiar with high and low level languages". I feel like the answer is obviously "no" since I don't know any low level languages. I do, however, have a basic idea of how assembly works.. But they are wanting me to actually know how to program in assembly / something comparable?

On January 08 2017 06:00 tofucake wrote:
"Algorithms" is a thing that can be done in any language. This statement confuses me.

On January 08 2017 06:00 tofucake wrote:
"Algorithms" is a thing that can be done in any language. This statement confuses me.

On January 10 2017 00:53 travis wrote:
yeah I guess I could have just tested it, which I kind of did but not in a proper context

for the life of me I can't figure out what this program is doing

I am doing this little online coding game for fun and the question is to take a list of elements and return a list of non unique elements. for example [5, 5, 3, 2, 2] would return [5,5,2,2]

my code

def checkio(data):
    #Your code here
    #It's main function. Don't remove this function
    #It's used for auto-testing and must return a result for check.  
    
    newlist = []
    
    for k in data:
        newlist.append(k)
    
    templist = []
    
    for n in newlist:
        if not n in templist:
            templist.append(n)
            newlist.remove(n)
            
    for j in data:
        if not j in newlist:
            data.remove(j)
        

    
    return data

I'd expect this to work, and for some situations it does seem to, but when the test passes [1, 2, 3, 1, 3] I seem to return 1, 2, 3, 1, 3 back. which doesn't make sense to me


my thinking is that I make an empty list
make a copy of data to play with

take 1 of each element in my copy, put them in my empty list and remove them from my copy

which should leave me with

data = [1, 2, 3, 1, 3]
templist = [1, 2, 3]
newlist = [1, 3]

then for each element in data, if it isn't in newlist, remove it

which should leave me with data = [1, 3, 1, 3]

but it doesn't.

what am I doing wrong?


does the problem actually have something to do with concurrent modification?





disclaimer: I know there's probably methods to use and other ways that are probably easier. I'll find those out as I go along. Though if you want to tell me feel free



edit 2. yay I solved it, I did this:

def checkio(data):
    #Your code here
    #It's main function. Don't remove this function
    #It's used for auto-testing and must return a result for check.  
    
    copyList = []
    
    for j in data:
        copyList.append(j)
    
    for n in copyList:
        if copyList.count(n) == 1:
            data.remove(n)
        

    
    return data

and it looks like concurrent modification does mess it up so I can't modify a list as I iterate. is that something that tends to happen in all languages?

On January 10 2017 00:53 travis wrote:
and it looks like concurrent modification does mess it up so I can't modify a list as I iterate. is that something that tends to happen in all languages?