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  • CSV parser in C++

    - by User1
    All I need is a good CSV file parser for C++. At this point it can really just be a comma-delimited parser (ie don't worry about escaping new lines and commas). The main need is a line-by-line parser that will return a vector for the next line each time the method is called. I found this article which looks quite promising: http://www.boost.org/doc/libs/1_35_0/libs/spirit/example/fundamental/list_parser.cpp I've never used Boost's Spirit, but am willing to try it. Is it overkill/bloated or is it fast and efficient? Does anyone have faster algorithms using STL or anything else? Thanks!

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  • Finding a Eulerian Tour

    - by user590903
    I am trying to solve a problem on Udacity described as follows: # Find Eulerian Tour # # Write a function that takes in a graph # represented as a list of tuples # and return a list of nodes that # you would follow on an Eulerian Tour # # For example, if the input graph was # [(1, 2), (2, 3), (3, 1)] # A possible Eulerian tour would be [1, 2, 3, 1] I came up with the following solution, which, while not as elegant as some of the recursive algorithms, does seem to work within my test case. def find_eulerian_tour(graph): tour = [] start_vertex = graph[0][0] tour.append(start_vertex) while len(graph) > 0: current_vertex = tour[len(tour) - 1] for edge in graph: if current_vertex in edge: if edge[0] == current_vertex: current_vertex = edge[1] else: current_vertex = edge[0] graph.remove(edge) tour.append(current_vertex) break return tour graph = [(1, 2), (2, 3), (3, 1)] print find_eulerian_tour(graph) >> [1, 2, 3, 1] However, when submitting this, I get rejected by the grader. I am doing something wrong? I can't see any errors.

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  • help in the Donalds B. Johnson's algorithm, i cannot understand the pseudo code (PART II)

    - by Pitelk
    Hi all , i cannot understand a certain part of the paper published by Donald Johnson about finding cycles (Circuits) in a graph. More specific i cannot understand what is the matrix Ak which is mentioned in the following line of the pseudo code : Ak:=adjacency structure of strong component K with least vertex in subgraph of G induced by {s,s+1,....n}; to make things worse some lines after is mentins " for i in Vk do " without declaring what the Vk is... As far i have understand we have the following: 1) in general, a strong component is a sub-graph of a graph, in which for every node of this sub-graph there is a path to any node of the sub-graph (in other words you can access any node of the sub-graph from any other node of the sub-graph) 2) a sub-graph induced by a list of nodes is a graph containing all these nodes plus all the edges connecting these nodes. in paper the mathematical definition is " F is a subgraph of G induced by W if W is subset of V and F = (W,{u,y)|u,y in W and (u,y) in E)}) where u,y are edges , E is the set of all the edges in the graph, W is a set of nodes. 3)in the code implementation the nodes are named by integer numbers 1 ... n. 4) I suspect that the Vk is the set of nodes of the strong component K. now to the question. Lets say we have a graph G= (V,E) with V = {1,2,3,4,5,6,7,8,9} which it can be divided into 3 strong components the SC1 = {1,4,7,8} SC2= {2,3,9} SC3 = {5,6} (and their edges) Can anybody give me an example for s =1, s= 2, s= 5 what if going to be the Vk and Ak according to the code? The pseudo code is in my previous question in http://stackoverflow.com/questions/2908575/help-in-the-donalds-b-johnsons-algorithm-i-cannot-understand-the-pseudo-code and the paper can be found at http://stackoverflow.com/questions/2908575/help-in-the-donalds-b-johnsons-algorithm-i-cannot-understand-the-pseudo-code thank you in advance

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  • Boost Netbook Speed with an SD Card & ReadyBoost

    - by Matthew Guay
    Looking for a way to increase the performance of your netbook?  Here’s how you can use a standard SD memory card or a USB flash drive to boost performance with ReadyBoost. Most netbooks ship with 1Gb of Ram, and many older netbooks shipped with even less.  Even if you want to add more ram, often they can only be upgraded to a max of 2GB.  With ReadyBoost in Windows 7, it’s easy to boost your system’s performance with flash memory.  If your netbook has an SD card slot, you can insert a memory card into it and just leave it there to always boost your netbook’s memory; otherwise, you can use a standard USB flash drive the same way. Also, you can use ReadyBoost on any desktop or laptop; ones with limited memory will see the most performance increase from using it. Please Note:  ReadyBoost requires at least 256Mb of free space on your flash drive, and also requires minimum read/write speeds.  Most modern memory cards or flash drives meet these requirements, but be aware that an old card may not work with it. Using ReadyBoost Insert an SD card into your card reader, or connect a USB flash drive to a USB port on your computer.  Windows will automatically see if your flash memory is ReadyBoost capable, and if so, you can directly choose to speed up your computer with ReadyBoost. The ReadyBoost settings dialog will open when you select this.  Choose “Use this device” and choose how much space you want ReadyBoost to use. Click Ok, and Windows will setup ReadyBoost and start using it to speed up your computer.  It will automatically use ReadyBoost whenever the card is connected to the computer. When you view your SD card or flash drive in Explorer, you will notice a ReadyBoost file the size you chose before.  This will be deleted when you eject your card or flash drive. If you need to remove your drive to use elsewhere, simply eject as normal. Windows will inform you that the drive is currently being used.  Make sure you have closed any programs or files you had open from the drive, and then press Continue to stop ReadyBoost and eject your drive. If you remove the drive without ejecting it, the ReadyBoost file may still remain on the drive.  You can delete this to save space on the drive, and the cache will be recreated when you use ReadyBoost next time. Conclusion Although ReadyBoost may not make your netbook feel like a Core i7 laptop with 6GB of RAM, it will still help performance and make multitasking even easier.  Also, if you have, say, a memory stick and a flash drive, you can use both of them with ReadyBoost for the maximum benefit.  We have even noticed better battery life when multitasking with ReadyBoost, as it lets you use your hard drive less.  SD cards and thumb drives are relatively cheap today, and many of us have several already, so this is a great way to improve netbook performance cheaply. Similar Articles Productive Geek Tips Speed up Your Windows Vista Computer with ReadyBoostSet the Speed Dial as the Opera Startup PageAsk the Readers: What are Your Computer’s Hardware Specs?Understanding Windows Vista Aero Glass RequirementsReplace Google Chrome’s New Tab Page with Speed Dial TouchFreeze Alternative in AutoHotkey The Icy Undertow Desktop Windows Home Server – Backup to LAN The Clear & Clean Desktop Use This Bookmarklet to Easily Get Albums Use AutoHotkey to Assign a Hotkey to a Specific Window Latest Software Reviews Tinyhacker Random Tips DVDFab 6 Revo Uninstaller Pro Registry Mechanic 9 for Windows PC Tools Internet Security Suite 2010 Recycle ! Find That Elusive Icon with FindIcons Looking for Good Windows Media Player 12 Plug-ins? Find Out the Celebrity You Resemble With FaceDouble Whoa ! Use Printflush to Solve Printing Problems

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  • Is complete boost going to be included in C++0x?

    - by iammilind
    Many utilities of boost have been included as part of extended C++ TR1 currently. Is the complete boost library going to be included once the standard is officially out ? In other words, do I need boost library, if I have complete standard conforming C++11 compiler ? If not then any reason for that (Reliability cannot be an issue; as far as I know it's written by many people from standard committee) ?

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  • 5 ways the Exceptional DBA Award could boost your career

    - by Rebecca Amos
    Winning the Exceptional DBA Award won’t just get you full conference registration for the PASS Summit – it could also change your life and career. With a little help from our past winners, here are the top 5 ways the Exceptional DBA Award could take your career to the next level: 1. Recognition from your peers As 2009 winner Josef Richberg says, “Being recognized by your peers is the highest honor one can receive.” Whether you enter yourself, or are nominated by a friend or colleague, the fact that the winner is selected by the SQL Server community is a great chance for your peers to recognize your achievements as a DBA. 2. Boost your CV Winning the Exceptional DBA Award not only shows that you excel as a DBA, but that SQL Server experts think so too – a huge vote of confidence for any prospective employer. 2008 winner Dan McClain agrees, “It brings another level of 'wow' to my resume”. 3. Networking opportunities within the community Whether you want to increase your experience as a writer, speaker or blogger, winning the Exceptional DBA Award can open up new opportunities within the SQL Server community. Plus you’ll make new friends along the way, as Josef has discovered: “It is an unbelievable community that has become an extended family.” 4. Award ceremony at the world's largest technical SQL Server conference The Exceptional DBA Award is presented at the PASS Summit, giving you great networking opportunities and a chance to be seen by people throughout the SQL Server community. 5. Increased personal confidence Finally, the Exceptional DBA Award should give a huge boost to your personal confidence. Last year’s winner, Tracy Hamlin has certainly found this: “The recognition has given me new confidence and the drive to accomplish even loftier goals.” Read the full interview with our past winners to find out how why they’re encouraging you to enter this year’s Exceptional DBA Awards. Already inspired? Then why not get started on your entry straightaway: www.exceptionaldba.com

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  • How to implement generic callbacks in C++

    - by Kylotan
    Forgive my ignorance in asking this basic question but I've become so used to using Python where this sort of thing is trivial that I've completely forgotten how I would attempt this in C++. I want to be able to pass a callback to a function that performs a slow process in the background, and have it called later when the process is complete. This callback could be a free function, a static function, or a member function. I'd also like to be able to inject some arbitrary arguments in there for context. (ie. Implementing a very poor man's coroutine, in a way.) On top of that, this function will always take a std::string, which is the output of the process. I don't mind if the position of this argument in the final callback parameter list is fixed. I get the feeling that the answer will involve boost::bind and boost::function but I can't work out the precise invocations that would be necessary in order to create arbitrary callables (while currying them to just take a single string), store them in the background process, and invoke the callable correctly with the string parameter.

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  • Reading graph inputs for a programming puzzle and then solving it

    - by Vrashabh
    I just took a programming competition question and I absolutely bombed it. I had trouble right at the beginning itself from reading the input set. The question was basically a variant of this puzzle http://codercharts.com/puzzle/evacuation-plan but also had an hour component in the first line(say 3 hours after start of evacuation). It reads like this This puzzle is a tribute to all the people who suffered from the earthquake in Japan. The goal of this puzzle is, given a network of road and locations, to determine the maximum number of people that can be evacuated. The people must be evacuated from evacuation points to rescue points. The list of road and the number of people they can carry per hour is provided. Input Specifications Your program must accept one and only one command line argument: the input file. The input file is formatted as follows: the first line contains 4 integers n r s t n is the number of locations (each location is given by a number from 0 to n-1) r is the number of roads s is the number of locations to be evacuated from (evacuation points) t is the number of locations where people must be evacuated to (rescue points) the second line contains s integers giving the locations of the evacuation points the third line contains t integers giving the locations of the rescue points the r following lines contain to the road definitions. Each road is defined by 3 integers l1 l2 width where l1 and l2 are the locations connected by the road (roads are one-way) and width is the number of people per hour that can fit on the road Now look at the sample input set 5 5 1 2 3 0 3 4 0 1 10 0 2 5 1 2 4 1 3 5 2 4 10 The 3 in the first line is the additional component and is defined as the number of hours since the resuce has started which is 3 in this case. Now my solution was to use Dijisktras algorithm to find the shortest path between each of the rescue and evac nodes. Now my problem started with how to read the input set. I read the first line in python and stored the values in variables. But then I did not know how to store the values of the distance between the nodes and what DS to use and how to input it to say a standard implementation of dijikstras algorithm. So my question is two fold 1.) How do I take the input of such problems? - I have faced this problem in quite a few competitions recently and I hope I can get a simple code snippet or an explanation in java or python to read the data input set in such a way that I can input it as a graph to graph algorithms like dijikstra and floyd/warshall. Also a solution to the above problem would also help. 2.) How to solve this puzzle? My algorithm was: Find shortest path between evac points (in the above example it is 14 from 0 to 3) Multiply it by number of hours to get maximal number of saves Also the answer given for the variant for the input set was 24 which I dont understand. Can someone explain that also. UPDATE: I get how the answer is 14 in the given problem link - it seems to be just the shortest path between node 0 and 3. But with the 3 hour component how is the answer 24 UPDATE I get how it is 24 - its a complete graph traversal at every hour and this is how I solve it Hour 1 Node 0 to Node 1 - 10 people Node 0 to Node 2- 5 people TotalRescueCount=0 Node 1=10 Node 2= 5 Hour 2 Node 1 to Node 3 = 5(Rescued) Node 2 to Node 4 = 5(Rescued) Node 0 to Node 1 = 10 Node 0 to Node 2 = 5 Node 1 to Node 2 = 4 TotalRescueCount = 10 Node 1 = 10 Node 2= 5+4 = 9 Hour 3 Node 1 to Node 3 = 5(Rescued) Node 2 to Node 4 = 5+4 = 9(Rescued) TotalRescueCount = 9+5+10 = 24 It hard enough for this case , for multiple evac and rescue points how in the world would I write a pgm for this ?

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  • Problem with OOP Class Definitions

    - by oben
    Hi, this is Oben from Turkey. I work for my homework in C++ and i have some problems with multiply definitions. My graph class ; class Graph{ private: string name; //Graph name fstream* graphFile; //Graph's file protected: string opBuf; //Operations buffer int containsNode(string); //Query if a node is present Node* nodes; //Nodes in the graph int nofNodes; //Number of nodes in the graph public: static int nOfGraphs; //Number of graphs produced Graph(); //Constructors and destructor Graph(int); Graph(string); Graph(const Graph &); ~Graph(); string getGraphName(); //Get graph name bool addNode(string); //add a node to the graph bool deleteNode(string); //delete a node from the graph bool addEdge(string,string); //add an edge to the graph bool deleteEdge(string,string); //delete an edge from the graph void intersect(const Graph&); //intersect the graph with the <par> void unite(const Graph&); //intersect the graph with the <par> string toString(); //get string representation of the graph void acceptTraverse(BreadthFirst*); void acceptTraverse(DepthFirst *); }; and my traversal class; class Traversal { public: string *visitedNodes; virtual string traverse (const Graph & ); }; class BreadthFirst : public Traversal { public : BreadthFirst(); string traverse(); }; class DepthFirst : public Traversal { public : DepthFirst(); string traverse(); }; My problem is in traversal class , i need to declare Graph class at the same time , in graph class i need traversal class to declare. I have big problems with declerations :) Could you please help me ?

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  • Containers of reference_wrappers (comparison operators required?)

    - by kloffy
    If you use stl containers together with reference_wrappers of POD types, the following code works just fine: int i = 3; std::vector< boost::reference_wrapper<int> > is; is.push_back(boost::ref(i)); std::cout << (std::find(is.begin(),is.end(),i)!=is.end()) << std::endl; However, if you use non-POD types such as (contrived example): struct Integer { int value; bool operator==(const Integer& rhs) const { return value==rhs.value; } bool operator!=(const Integer& rhs) const { return !(*this == rhs); } }; It doesn't suffice to declare those comparison operators, instead you have to declare: bool operator==(const boost::reference_wrapper<Integer>& lhs, const Integer& rhs) { return boost::unwrap_ref(lhs)==rhs; } And possibly also: bool operator==(const Integer& lhs, const boost::reference_wrapper<Integer>& rhs) { return lhs==boost::unwrap_ref(rhs); } In order to get the equivalent code to work: Integer j = { 0 }; std::vector< boost::reference_wrapper<Integer> > js; js.push_back(boost::ref(j)); std::cout << (std::find(js.begin(),js.end(),j)!=js.end()) << std::endl; Now, I'm wondering if this is really the way it's meant to be done, since it seems impractical. It just seems there should be a simpler solution, e.g. templates: template<class T> bool operator==(const boost::reference_wrapper<T>& lhs, const T& rhs) { return boost::unwrap_ref(lhs)==rhs; } template<class T> bool operator==(const T& lhs, const boost::reference_wrapper<T>& rhs) { return lhs==boost::unwrap_ref(rhs); } There's probably a good reason why reference_wrapper behaves the way it does (possibly to accomodate non-POD types without comparison operators?). Maybe there already is an elegant solution and I just haven't found it.

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  • Using time facets on universal_time

    - by scooterman
    Hi all, on boost, to create a time facet to format an specified time we use the folowing: boost::local_time::local_time_facet* facet = new boost::local_time::local_time_facet("%Y%m%d %H:%M:%S.%f"); std::stringstream date_stream; date_stream.imbue(std::locale(date_stream.getloc(), facet)); date_stream << boost::local_time::local_microsec_clock::local_time(boost::local_time::time_zone_ptr()); How do I do the same thing, but using an universal clock: boost::posix_time::microsec_clock::universal_time() Thanks

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  • Reverse Bredth First Search in C#

    - by Ngu Soon Hui
    Anyone has a ready implementation of the Reverse Bredth First Search algorithm in C#? By Reverse Bredth First Search, I mean instead of searching a tree starting from a common node, I want to search the tree from the bottom and gradually converged to a common node. Let's see the below figure, this is the output of a Bredth First Search: In my reverse bredth first search, 9,10,11 and 12 will be the first few nodes found ( the order of them are not important as they are all first order). 5, 6, 7 and 8 are the second few nodes found, and so on. 1 would be the last node found. Any ideas or pointers?

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  • Reverse Breadth First traversal in C#

    - by Ngu Soon Hui
    Anyone has a ready implementation of the Reverse Breadth First traversal algorithm in C#? By Reverse Breadth First traversal , I mean instead of searching a tree starting from a common node, I want to search the tree from the bottom and gradually converged to a common node. Let's see the below figure, this is the output of a Breadth First traversal : In my reverse breadth first traversal , 9,10,11 and 12 will be the first few nodes found ( the order of them are not important as they are all first order). 5, 6, 7 and 8 are the second few nodes found, and so on. 1 would be the last node found. Any ideas or pointers? Edit: Change "Breadth First Search" to "Breadth First traversal" to clarify the question

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  • Reverse Breath First Search in C#

    - by Ngu Soon Hui
    Anyone has a ready implementation of the Reverse Breath First Search algorithm in C#? By Reverse Breath First Search, I mean instead of searching a tree starting from a common node, I want to search the tree from the bottom and gradually converged to a common node. Let's see the below figure, this is the output of a Breath First Search: In my reverse breath first search, 9,10,11 and 12 will be the first few nodes found ( the order of them are not important as they are all first order). 5, 6, 7 and 8 are the second few nodes found, and so on. 1 would be the last node found. Any ideas or pointers?

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  • directed unweighted graphs C

    - by fang_dejavu
    Hi, I'm planning to write a program in C that builds the adjacency list, performs the depth first search, performs the breadth first search, and performs the topological sort. Where can I get some info about this subject in C? Any help is appreciated

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  • Drawing Directed Acyclic Graphs: Using DAG property to improve layout/edge routing?

    - by Robert Fraser
    Hi, Laying out the verticies in a DAG in a tree form (i.e. verticies with no in-edges on top, verticies dependent only on those on the next level, etc.) is rather simple. However, is there a simple algorithm to do this that minimizes edge crossing? (For some graphs, it may be impossible to completely eliminate edge crossing.) A picture says a thousand words, so is there an algorithm that would suggest: instead of:

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  • how a thread can signal when it's finished?

    - by Kyle
    #include <iostream> #include <boost/thread.hpp> using std::endl; using std::cout; using namespace boost; mutex running_mutex; struct dostuff { volatile bool running; dostuff() : running(true) {} void operator()(int x) { cout << "dostuff beginning " << x << endl; this_thread::sleep(posix_time::seconds(2)); cout << "dostuff is done doing stuff" << endl; mutex::scoped_lock running_lock(running_mutex); running = false; } }; bool is_running(dostuff& doer) { mutex::scoped_lock running_lock(running_mutex); return doer.running; } int main() { cout << "Begin.." << endl; dostuff doer; thread t(doer, 4); if (is_running(doer)) cout << "Cool, it's running.\n"; this_thread::sleep(posix_time::seconds(3)); if (!is_running(doer)) cout << "Cool, it's done now.\n"; else cout << "still running? why\n"; // This happens! :( return 0; } Why is the output of the above program: Begin.. Cool, it's running. dostuff beginning 4 dostuff is done doing stuff still running? why How can dostuff correctly flag when it is done? I do not want to sit around waiting for it, I just want to be notified when it's done.

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  • Best boost to productivity : SSD or second screen ?

    - by jfoucher
    Within the same budget, which do you think would be the best boost to productivity for general web development : An SSD as boot drive, or a second screen ? I currently use a 16.4" laptop with full HD screen and 7200 RPM HDD Thanks EDIT: In light of the answers so far, I add that I work at home and while I have a home office with a proper desk, I'm just as often coding sitting on the sofa in the living room.

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  • 5 Easy Ways to Get High PR Links to Boost Your Site in Google

    High PR links are some of the most valuable aspects in any link-building & SEO campaign. Not only do these links make Google respect your site more, but they can also boost your site's ranking overnight. Here are 5 places to get high quality links that will do a lot of good to your site's ranking in Google.

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