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  • Can you tell me why this generates time limit exceeded in spoj(Prime Number Generator)

    - by magiix
    #include<iostream> #include<string.h> #include<math.h> using namespace std; bool prime[1000000500]; void generate(long long end) { memset(prime,true,sizeof(prime)); prime[0]=false; prime[1]=false; for(long long i=0;i<=sqrt(end);i++) { if(prime[i]==true) { for(long long y=i*i;y<=end;y+=i) { prime[y]=false; } } } } int main() { int n; long long b,e; scanf("%d",&n); while(n--) { cin>>b>>e; generate(e); for(int i=b;i<e;i++) { if(prime[i]) printf("%d\n",i); } } return 0; } That's my code for spoj prime generator. Altought it generates the same output as another accepted code ..

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  • Is there a Java equivalent to libevent?

    - by JoelPM
    I've written a high-throughput server that handles each request in its own thread. For requests coming in it is occasionally necessary to do RPCs to one or more back-ends. These back-end RPCs are handled by a separate queue and thread-pool, which provides some bounding on the number of threads created and the maximum number of connections to the back-end (it does some caching to reuse clients and save the overhead of constantly creating connections). Having done all this, though, I'm beginning to think an event-based architecture would be more efficient. In searching around I haven't found any equivalents to libevent for Java, but maybe I'm not looking in the right place? Mina-statemachine from Apache was the closest thing I found, but it looks more verbose than I need and there's no real release available. Any suggestions?

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  • Are lambda expressions/delegates in C# "pure", or can they be?

    - by Bob
    I recently asked about functional programs having no side effects, and learned what this means for making parallelized tasks trivial. Specifically, that "pure" functions make this trivial as they have no side effects. I've also recently been looking into LINQ and lambda expressions as I've run across examples many times here on StackOverflow involving enumeration. That got me to wondering if parallelizing an enumeration or loop can be "easier" in C# now. Are lambda expressions "pure" enough to pull off trivial parallelizing? Maybe it depends on what you're doing with the expression, but can they be pure enough? Would something like this be theoretically possible/trivial in C#?: Break the loop into chunks Run a thread to loop through each chunk Run a function that does something with the value from the current loop position of each thread For instance, say I had a bunch of objects in a game loop (as I am developing a game and was thinking about the possibility of multiple threads) and had to do something with each of them every frame, would the above be trivial to pull off? Looking at IEnumerable it seems it only keeps track of the current position, so I'm not sure I could use the normal generic collections to break the enumeration into "chunks". Sorry about this question. I used bullets above instead of pseudo-code because I don't even know enough to write pseudo-code off the top of my head. My .NET knowledge has been purely simple business stuff and I'm new to delegates and threads, etc. I mainly want to know if the above approach is good for pursuing, and if delegates/lambdas don't have to be worried about when it comes to their parallelization.

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  • how to use quad core CPU in application

    - by Mayank
    For using all the cores of a quad core processor what do I need to change in my code is it about adding support of multi threading or is it which is taken care by OS itself. I am having FreeBSD and language I am using is C++. I want to give complete CPU cycles to my application at least 90%.

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  • Naming Suggestions For A Function Providing Method Chaining In A Different Way

    - by sid3k
    I've coded an experimental function which makes passed objects chainable by using high order functions. It's name is "chain" for now, and here is a usage example; chain("Hello World") (print) // evaluates print function by passing "Hello World" object. (console.log,"Optional","Parameters") (returnfrom) // returns "Hello World" It looks lispy but behaves very different since it's coded in a C based language, I don't know if there is a name for this idiom and I couldn't any name more suitable than "chain". Any ideas, suggestions?

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  • State Monad, why not a tuple?

    - by thr
    I've just wrapped my head around monads (at least I'd like to think I have) and more specifically the state monad, which some people that are way smarter then me figured out, so I'm probably way of with this question. Anyway, the state monad is usually implemented with a M<'a as something like this (F#): type State<'a, 'state> = State of ('state -> 'a * 'state) Now my question: Is there any reason why you couldn't use a tuple here? Other then the possible ambiguity between MonadA<'a, 'b> and MonadB<'a, 'b> which would both become the equivalent ('a * 'b) tuple. Edit: Added example for clarity type StateMonad() = member m.Return a = (fun s -> a, s) member m.Bind(x, f) = (fun s -> let a, s_ = x s in f a s_) let state = new StateMonad() let getState = (fun s -> s, s) let setState s = (fun _ -> (), s) let execute m s = m s |> fst

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  • Do you have any tips for commenting code?

    - by Rob Wells
    G'day, I've read both of Steve McConnell's excellent Code Complete books "Code Complete" and "Code Complete 2" and was wondering if people have any other suggestions for commenting code.co My commenting mantra could be summed up by the basic idea of expressing "what the code below cannot say". While enjoying this interesting blog post by Jeff about commenting I was still left wondering "When coding, when do you feel a comment is required?"

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  • How to return the output of a recursive function in Clojure

    - by Silanglaya Valerio
    Hi everyone! I'm new to functional languages and clojure, so please bear with me... I'm trying to construct a list of functions, with either random parameters or constants. The function that constructs the list of functions is already working, though it doesn't return the function itself. I verified this using println. Here is the snippet: (def operations (list #(- %1 %2) #(+ %1 %2) #(* %1 %2) #(/ %1 %2))) (def parameters (list \u \v \w \x \y \z)) (def parameterlistcount 6) (def paramcount 2) (def opcount 4) (defn generateFunction "Generates a random function list" ([] (generateFunction 2 4 0.5 0.6 '())) ([pc maxdepth fp pp function] (if (and (> maxdepth 0) (< (rand) fp)) (dotimes [i 2] (println(conj (generateFunction pc (dec maxdepth) fp pp function) {:op (nth operations (rand-int opcount))}))) (if (and (< (rand) pp) (> pc 0)) (do (dec pc) (conj function {:param (nth parameters (rand-int parameterlistcount))})) (conj function {:const (rand-int 100)}))))) Any help will be appreciated, thanks!

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  • Suggestions for a PHP programmer wanting to create a timer app for an internet cafe

    - by grokker
    Hi, I was asked by a friend to make a timer app for his small internet cafe. He wants to have timers on each client PCs. The timers indicate how much time has been spent by the customer. On the PC that he uses, there's another program that has the overview of all the timers and there's a button for each client PCs that allows him to blacken out the screen. It's not automatic hence the button. The problem is I haven't done any desktop apps before so that's why I'm asking you guys (the awesome people at SO) for suggestions/advice on what language/tool to use. A little info about me: I did Java but haven't tried Swing though. I know a bit about Python and Ruby too. I don't mind learning new languages as long as I get to finish or get a prototype up and running. He doesn't mind if I could show him a prototype, it's actually for me. It gives me satisfaction to see I'm progressing. I'm not planning on asking him to pay me for doing this. Whatever he gives me is fine. P.S. He's using Windows XP

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  • Sending multiline message via sockets without closing the connection

    - by Yasir Arsanukaev
    Hello folks. Currently I have this code of my client-side Haskell application: import Network.Socket import Network.BSD import System.IO hiding (hPutStr, hPutStrLn, hGetLine, hGetContents) import System.IO.UTF8 connectserver :: HostName -- ^ Remote hostname, or localhost -> String -- ^ Port number or name -> IO Handle connectserver hostname port = withSocketsDo $ do -- withSocketsDo is required on Windows -- Look up the hostname and port. Either raises an exception -- or returns a nonempty list. First element in that list -- is supposed to be the best option. addrinfos <- getAddrInfo Nothing (Just hostname) (Just port) let serveraddr = head addrinfos -- Establish a socket for communication sock <- socket (addrFamily serveraddr) Stream defaultProtocol -- Mark the socket for keep-alive handling since it may be idle -- for long periods of time setSocketOption sock KeepAlive 1 -- Connect to server connect sock (addrAddress serveraddr) -- Make a Handle out of it for convenience h <- socketToHandle sock ReadWriteMode -- Were going to set buffering to LineBuffering and then -- explicitly call hFlush after each message, below, so that -- messages get logged immediately hSetBuffering h LineBuffering return h sendid :: Handle -> String -> IO String sendid h id = do hPutStr h id -- Make sure that we send data immediately hFlush h -- Retrieve results hGetLine h The code portions in connectserver are from this chapter of Real World Haskell book where they say: When dealing with TCP data, it's often convenient to convert a socket into a Haskell Handle. We do so here, and explicitly set the buffering – an important point for TCP communication. Next, we set up lazy reading from the socket's Handle. For each incoming line, we pass it to handle. After there is no more data – because the remote end has closed the socket – we output a message about that. Since hGetContents blocks until the server closes the socket on the other side, I used hGetLine instead. It satisfied me before I decided to implement multiline output to client. I wouldn't like the server to close a socket every time it finishes sending multiline text. The only simple idea I have at the moment is to count the number of linefeeds and stop reading lines after two subsequent linefeeds. Do you have any better suggestions? Thanks.

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  • Subroutine & GoTo design

    - by sub
    I have a strange question concerning subroutines: As I'm creating a minimal language and I don't want to add high-level loops like while or for I was planning on just adding gotos to keep it Turing-Complete. Now I thought, eww - gotos - I wouldn't want to program in that language if I had to use gotos so often. So I thought about adding subroutines instead. I see the difference as the following: gotos Go to (captain obvious) a previously defined point and continue executing the program from there. Leads to hardly understandable and buggy code, I think that's a fact. subroutines Similiar: You define their starting point somewhere, as you call them the program jumps there - but the subroutine can go back to the point it was called from with return. Okay. Why didn't I just add the more function-like, nice looking subroutines? Because: In order to make return work if I call subroutines from within subroutines from within other subroutines, I'd have to use a stack containing the point where the currently running subroutine came from at top. That would then mean that I would, if I create loops using the subroutines, end up with an extremely memory-eating, overflowing stack with return locations. Not good. Don't think of my subroutines as functions. They are just gotos that return to the point they were called from, they don't actually give back values like the return x; statement in nearly all today's languages. Now to my actual questions: How can I solve the above problem with the stack overflow on loops with subroutines? Do I have to add a separate goto language construct without the return option? Assembler doesn't have loops but as I have seen myJumpPoint:, jnz, jz, retn. That means to me that there must also be a stack containing all the return locations. Am I right with that? What about long running loops then? Don't they overflow the stack/eat memory then? Am I getting the retn symbol in assembler totally wrong? If yes, please explain it to me.

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  • Using TTMessageController with Multiple Data Sources

    - by PF1
    Hi Everyone: I am wondering if there is some way to set a separate .datasource for each custom field in a TTMessageController. Right now I am using a TTMessageController subclass (and referencing the data source controller delegate) and simply setting the data source of the message controller to self. But I only believe this will work for one field with one set of options. Thanks for any help!

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  • How well do zippers perform in practice, and when should they be used?

    - by Rob
    I think that the zipper is a beautiful idea; it elegantly provides a way to walk a list or tree and make what appear to be local updates in a functional way. Asymptotically, the costs appear to be reasonable. But traversing the data structure requires memory allocation at each iteration, where a normal list or tree traversal is just pointer chasing. This seems expensive (please correct me if I am wrong). Are the costs prohibitive? And what under what circumstances would it be reasonable to use a zipper?

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  • Broadcast-style Bluetooth using Sockets on the iPhone?

    - by Kyle
    Is there any way to open a broadcast bluetooth socket, take a listen and send replies? I want a proper peer to peer system where I broadcast and listen for broadcasts in an area. That way, variable clients can mingle. Is this possible? My theory is this: If GameKit can sit around wasting 25 seconds of the users time whilst having access to a broadcast socket, can't I? Or, must I be in kernel mode for such access? I'm not really sure where the proper bluetooth headers are as well. Thanks for reading!

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  • Windows Phone 7 Connect to SharePoint via SOAP

    - by Mitchell Skurnik
    I am making my second application for the Windows 7 Phone Series platform and I cannot seem to connect to a SharePoint server using https. 99% of the following is not my code. I have borrowed it from http://blog.daisley-harrison.com/blog/post/Practical-Silverlight-and-SharePoint-Integration-Part-Two.aspx untill I can further understand how SOAP works in W7P Series. I know that I need some way of sending credentials over but the win 7 API does not seem to let you. ServiceReferences.ClientConfig <?xml version="1.0" encoding="utf-8"?> <configuration> <system.serviceModel> <bindings> <basicHttpBinding> <binding name="ViewsSoap" maxBufferSize="2147483647" maxReceivedMessageSize="2147483647" transferMode="Buffered"> <security mode="TransportCredentialOnly"/> </binding> </basicHttpBinding> </bindings> <client> <endpoint address="https://my.secureconnection.com/_vti_bin/views.asmx" binding="basicHttpBinding" bindingConfiguration="ViewsSoap" contract="SharePointListService.ViewsSoap" name="ViewsSoap" /> </client> </system.serviceModel> </configuration> This is my maincode page: public partial class MainPage : PhoneApplicationPage { public MainPage() { InitializeComponent(); SupportedOrientations = SupportedPageOrientation.Portrait | SupportedPageOrientation.Landscape; try { Uri serviceUri = new Uri("https://my.secureconnection.com" + SERVICE_LISTS_URL); BasicHttpBinding binding; if (serviceUri.Scheme == "https") { binding = new BasicHttpBinding(BasicHttpSecurityMode.Transport); } else { binding = new BasicHttpBinding(BasicHttpSecurityMode.None); } EndpointAddress endpoint = new EndpointAddress(serviceUri); ListsSoapClient listSoapClient = new ListsSoapClient(binding, endpoint); NetworkCredential creds = new NetworkCredential("administrator", "iSynergy1", "server001"); //listSoapClient.ClientCredentials.Windows.AllowedImpersonationLevel = TokenImpersonationLevel.Identification; //listSoapClient.ClientCredentials.Windows.ClientCredential = creds; listSoapClient.GetListCollectionCompleted += new EventHandler<GetListCollectionCompletedEventArgs>(listSoapClient_GetListCollectionCompleted); listSoapClient.GetListCollectionAsync(); } catch (Exception exception) { handleException("Failed to get list collection", exception); } } #region ShowExceptionDetail Property public static readonly DependencyProperty ShowExceptionDetailDependencyProperty = DependencyProperty.Register("ShowExceptionDetail",typeof(bool),typeof(Page),new PropertyMetadata(true)); public bool ShowExceptionDetail { get { return (bool)GetValue(ShowExceptionDetailDependencyProperty); } set { SetValue(ShowExceptionDetailDependencyProperty, value); } } #endregion private void handleException(string context, Exception exception) { this.Dispatcher.BeginInvoke(delegate() { bool showExceptionDetail = this.ShowExceptionDetail; string message = ""; Exception next = exception; do { if (message.Length > 0) { message += ";" + Environment.NewLine; } if (next.Message == null || next.Message.Length == 0) { message += next.GetType().FullName; } else { message += next.Message; } if (showExceptionDetail) { if (next.Data.Count > 0) { bool first = true; message += " {"; foreach (string key in next.Data.Keys) { if (first) { first = false; } else { message += ", "; } message += key + "=\"" + next.Data[key] + "\""; } message += "}"; } if (next.InnerException != next) { next = next.InnerException; continue; } } next = null; } while (next != null); MessageBox.Show(message, context, MessageBoxButton.OK); }); } private const string SERVICE_LISTS_URL = "/_vti_bin/lists.asmx"; void listSoapClient_GetListCollectionCompleted(object sender, GetListCollectionCompletedEventArgs e) { try { myList.Text = e.Result.ToString(); } catch (Exception exception) { handleException("Failed to get list collection", exception); } } } When I run this and it gets to the "ListsSoapClient" part, it breaks. If you dig down into the error output it says access is denied. I have tried various methods of sending credentials but none seem to work. "ClientCredentials.Windows" is not supported and ClientCredentials.UsersName.Username is read only.

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  • How do programmers work together on a project?

    - by Laith J
    Hello, I've always programmed alone, I'm still a student so I never programmed with anyone else, I haven't even used a version control system before. I'm working on a project now that requires knowledge of how programmers work together on a piece of software in a company. How is the software compiled? Is it from the version control system? Is it by individual programmers? Is it periodic? Is it when someone decides to build or something? Are there any tests that are done to make sure it "works"? Anything will do. Thanks.

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  • getting started with lex

    - by cambr
    I need to format some hexdump like this: 00010: 02 03 04 05 00020: 02 03 04 08 00030: 02 03 04 08 00010: 02 03 04 05 00020: 02 03 04 05 02 03 04 05 02 03 04 08 to 02 03 04 05 02 03 04 08 02 03 04 02 03 04 05 02 03 04 05 02 03 04 05 02 03 04 a) remove the address fields, if present b) remove any 08 at the end of a paragraph (followed by an empty line) c) remove any empty lines How can this be done using lex? thanks!

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  • How to simply this logic/code?

    - by Tattat
    I want to write an apps that accepts user command. The user command is used in this format: command -parameter For example, the app can have "Copy", "Paste", "Delete" command I am thinking the program should work like this : public static void main(String args[]){ if(args[0].equalsIgnoreCase("COPY")){ //handle the copy command } else if(args[0].equalsIgnoreCase("PASTE")){ //handle the copy command }/** code skipped **/ } So, it works, but I think it will become more and more complex when I have more command in my program, also, it is different to read. Any ideas to simply the logic?

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  • On WindowsMobile, how can i tell what other processes are reserving shared memory space?

    - by glutz78
    On WindowMobile 6.1, I am using VirtualAlloc to reserve 2MB chunks, which will return me an address from the large shared memory area so allocations do not count against my per process virtual space. (doc here: http://msdn.microsoft.com/en-us/library/aa908768.aspx) However, on some devices i notice that I am not able to reserve memory after a certain point. VirtualAlloc will return NULL (getlasterror() says out of memory). The only explanation for this that I see is that another process has already reserved a bunch of memory and my process is therefore unable to. Any idea where I can find a tool to show me the shared mem region of a WM device? Thanks.

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  • How do I compile a module in User Mode Linux

    - by Zach
    Having a tough time compiling a module for User Mode Linux. I just need a basic way to compile a very basic module in user mode linux and cannot seem to get it to work. I checked out the how-to on sourceforge for UML but had no luck. Anyone have a working example of what it takes? Thanks!

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