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Search found 1898 results on 76 pages for 'structures'.

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  • LRU cache design

    - by user297850
    Least Recently Used (LRU) Cache is to discard the least recently used items first How do you design and implement such a cache class? The design requirements are as follows: 1) find the item as fast as we can 2) Once a cache misses and a cache is full, we need to replace the least recently used item as fast as possible. How to analyze and implement this question in terms of design pattern and algorithm design?

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  • Referencing a union inside a structure using union tag gives incorrect address

    - by AlanKley
    I had a need to declare a union inside a structure as defined below: struct MyStruct { int m_DataType; DWORD m_DataLen; union theData { char m_Buff [_MAX_PATH]; struct MyData m_myData; } m_Data; }; Initially, I tried accessing the union data as follows (before I added the m_Data declaration): MyStruct m_myStruct; char* pBuff = m_myStruct.theData::m_Buff; This compiles but returns to pBuff a pointer to the beginning of the MyStruct structure which caused me to overwrite the m_DataType & m_DataLength members when I thought I was writing to the m_Buff buffer. I am using Visual Studio 2008. Can anyone explain this unexpected behavior? Thanks.

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  • The subscription model behind CSS selectors?

    - by Martin Kristiansen
    With CSS selectors a query string body > h1.span subscribes to a specific type of nodes in the tree. Does anyone know how this is done? Selectors for transformations, how does the browser select the result set? And is there a trick to making it efficient? I imagine there being some sort of hierarchical type-tree for the entire structure to which the nodes subscribe and which is what is used when doing the selector queries — but this is only a guess. Does anyone know the real answer? Or even more interesting, what would be the best way to do dynamic lookups on a tree based on jQuery/CSS search queries?

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  • Database structure - To join or not to join

    - by Industrial
    Hi! We're drawing up the database structure with the help of mySQL Workbench for a new app and the number of joins required to make a listing of the data is increasing drastically as the many-to-many relationships increases. The application will be quite read-heavy and have a couple of hundred thousand rows per table. The questions: Is it really that bad to merge tables where needed and thereby reducing joins? Should we start looking at horizontal partitioning? (in conjunction with merging tables) Is there a better way then pivot tables to take care of many-to-many relationships? We discussed about instead storing all data in serialized text columns and having the application make the sorting instead of the database, but this seems like a very bad idea, even though that the database will be heavily cached. What do you think? Thanks!

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  • Binary Search Tree in Java

    - by John R
    I want to make a generic BST, that can be made up of any data type, but i'm not sure how I could add things to the tree, if my BST is generic. All of my needed code is below. I want my BST made up of Locations, and sorted by the x variable. Any help is appreciated. Major thanks for looking. public void add(E element) { if (root == null) root = element; if (element < root) add(element, root.leftChild); if (element > root) add(element, root.rightChild); else System.out.println("Element Already Exists"); } private void add(E element, E currLoc) { if (currLoc == null) currLoc = element; if (element < root) add(element, currLoc.leftChild); if (element > root) add(element, currLoc.rightChild); else System.out.println("Element Already Exists); } Other Code public class BinaryNode<E> { E BinaryNode; BinaryNode nextBinaryNode; BinaryNode prevBinaryNode; public BinaryNode() { BinaryNode = null; nextBinaryNode = null; prevBinaryNode = null; } } public class Location<AnyType> extends BinaryNode { String name; int x,y; public Location() { name = null; x = 0; y = 0; } public Location(String newName, int xCord, int yCord) { name = newName; x = xCord; y = yCord; } public int equals(Location otherScene) { return name.compareToIgnoreCase(otherScene.name); } }

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  • What is the best Binary Decision Diagram library for Java?

    - by reprogrammer
    A Binary Decision Diagram (BDD) is a data structure to represent boolean functions. I'd like use this data structure in a Java program. My search for Java based BDD libraries resulted into the following packages. Java Decision Diagram Libraries JavaBDD JDD JBDD bddbddb If you know of any other BDD libraries available for Java programs, please let me know so that I add it to the list above. If you have used any of these libraries, please tell me about your experience with the library. In particular, I'd like you to compare the available libraries along the following dimensions. Quality. Is the library mature and reasonably bug free? Performance. How do you evaluate the performance of the library? Support. Could you easily get support whenever you encountered a problem with the library? Was the library well documented? Ease of use. Was the API well designed? Could you install and use the library quickly and easily? Please mention the version of the library that you are evaluating.

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  • Data Structure Behind Amazon S3s Keys (Filtering Data Structure)

    - by dimo414
    I'd like to implement a data structure similar to the lookup functionality of Amazon S3. For those of you who don't know what I'm taking about, Amazon S3 stores all files at the root, but allows you to look up groups of files by common prefixes in their names, therefore replicating the power of a directory tree without the complexity of it. The catch is, both lookup and filter operations are O(1) (or close enough that even on very large buckets - S3's disk equivalents - both operations might as well be O(1))). So in short, I'm looking for a data structure that functions like a hash map, with the added benefit of efficient (at the very least not O(n)) filtering. The best I can come up with is extending HashMap so that it also contains a (sorted) list of contents, and doing a binary search for the range that matches the prefix, and returning that set. This seems slow to me, but I can't think of any other way to do it. Does anyone know either how Amazon does it, or a better way to implement this data structure?

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  • What is validating a binary search tree?

    - by dotnetdev
    I read on here of an exercise in interviews known as validating a binary search tree. How exactly does this work? What would one be looking for in validating a binary search tree? I have written a basic search tree, but never heard of this concept. Thanks

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  • JSON and Microformats

    - by Tauren
    I'm looking for opinions on whether microformats should be used to name JSON elements. For instance, there is a microformat for physical addresses, that looks like this: <div class="adr"> <div class="street-address">665 3rd St.</div> <div class="extended-address">Suite 207</div> <span class="locality">San Francisco</span>, <span class="region">CA</span> <span class="postal-code">94107</span> <div class="country-name">U.S.A.</div> </div> There is a document available on using JSON and Microformats. The information above could be represented as JSON data like this: "adr": { "street-address":"665 3rd St.", "extended-address":"Suite 207", "locality":"San Fransicso", "region":"CA", "postal-code":"94107", "country-name":"U.S.A." }, The issue I have with this is that I'd like my JSON data to be as lightweight as possible, but still human readable. While still supporting international addresses, I would prefer something like this: "address": { "street":"665 3rd St.", "extended":"Suite 207", "locality":"San Fransicso", "region":"CA", "code":"94107", "country":"U.S.A." }, If I'm designing a new JSON API right now, does it make sense to use microformats from the start? Or should I not really worry about it? Is there some other standard that is more specific to JSON that I should look at?

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  • Best Data Structure For Time Series Data

    - by TriParkinson
    Hi all, I wonder if someone could take a minute out of their day to give their two cents on my problem. I would like some suggestions on what would be the best data structure for representing, on disk, a large data set of time series data. The main priority is speed of insertion, with other priorities in decreasing order; speed of retrieval, size on disk, size in memory, speed of removal. I have seen that B+ trees are often used in database because of their fast search times, but how about for fast insertion times? Is a linked list really the way to go? Thanks in advance for your time, Tri

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  • ByteBuffer recycling class

    - by Chris Dennett
    Hi everyone, I'm wonder how I'd code up a ByteBuffer recycling class that can get me a ByteBuffer which is at least as big as the specified length, and which can lock up ByteBuffer objects in use to prevent their use while they are being used by my code. This would prevent re-construction of DirectByteBuffers and such over and over, instead using existing ones. Is there an existing Java library which can do this very effectively? I know Javolution can work with object recycling, but does that extend to the ByteBuffer class in this context with the requirements set out? Cheers, Chris

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  • Optimize mysql table ?

    - by fabien-barbier
    Here is my actual table schema (I'm using Mysql) : Table experiment : code(int) sample_1_id sample_2_id ... until ... sample_12_id rna_1_id rna_2_id ... until ... rna_12_id experiment_start How can I optimize both part : sample_n_id and rna_n_id (all are bigint(20) and allow null=true) ? About values : we can have : ex : sample_1_id = 2 , Sample_2_id = 5 , ... Note : values can be updated. Ideas ? Thanks.

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  • create graph using adjacency list

    - by sum1needhelp
    #include<iostream> using namespace std; class TCSGraph{ public: void addVertex(int vertex); void display(); TCSGraph(){ head = NULL; } ~TCSGraph(); private: struct ListNode { string name; struct ListNode *next; }; ListNode *head; } void TCSGraph::addVertex(int vertex){ ListNode *newNode; ListNode *nodePtr; string vName; for(int i = 0; i < vertex ; i++ ){ cout << "what is the name of the vertex"<< endl; cin >> vName; newNode = new ListNode; newNode->name = vName; if (!head) head = newNode; else nodePtr = head; while(nodePtr->next) nodePtr = nodePtr->next; nodePtr->next = newNode; } } void TCSGraph::display(){ ListNode *nodePtr; nodePtr = head; while(nodePtr){ cout << nodePtr->name<< endl; nodePtr = nodePtr->next; } } int main(){ int vertex; cout << " how many vertex u wan to add" << endl; cin >> vertex; TCSGraph g; g.addVertex(vertex); g.display(); return 0; }

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  • Effects of changing a node in a binary tree

    - by eSKay
    Suppose I want to change the orange node in the following tree. So, the only other change I'll need to make is in the left pointer of the green node. The blue node will remain the same. Am I wrong somewhere? Because according to this article (that explains zippers), even the blue node needs to be changed. Similarly, in this picture (recolored) from the same article, why do we change the orange nodes at all (when we change x)?

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  • Array Vs. Linked List

    - by Onorio Catenacci
    I apologize--this question may be a bit open-ended but I think there are probably definite, quantifiable answers to it so I'll post it anyway. A person I know is trying to learn C++ and software development (+1 to him) and he asked me why someone would want to use a linked list in preference to an array. Coding a linked list is, no doubt, a bit more work than using an array and he wondered what would justify the additional effort. I gave him the answer I know: insertion of new elements is trivial in linked list but it's a major chore in an array. But then I got to thinking about it a bit more. Besides the ease of insertion of a new element into a linked list are there other advantages to using a linked list to store a set of data vs. storing it in an array? As I said, I'm not meaning to start a long and drawn-out discussion. I'm just looking for other reasons that a developer might prefer a linked list to an array.

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  • hash of array in objective-c, how?

    - by Horace Ho
    How is a hash of integer array can be represented in objective-c? Here is the ruby hash as an example: hi_scores = { "John" => [1, 1000], "Mary" => [2, 8000], "Bob" => [5, 2000] } such that can be accessed by: puts hi_scores["Mary"][1] => 8000 hopefully easy to serialize too. Thanks!

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  • adding nodes to a binary search tree randomly deletes nodes

    - by SDLFunTimes
    Hi, stack. I've got a binary tree of type TYPE (TYPE is a typedef of data*) that can add and remove elements. However for some reason certain values added will overwrite previous elements. Here's my code with examples of it inserting without overwriting elements and it not overwriting elements. the data I'm storing: struct data { int number; char *name; }; typedef struct data data; # ifndef TYPE # define TYPE data* # define TYPE_SIZE sizeof(data*) # endif The tree struct: struct Node { TYPE val; struct Node *left; struct Node *rght; }; struct BSTree { struct Node *root; int cnt; }; The comparator for the data. int compare(TYPE left, TYPE right) { int left_len; int right_len; int shortest_string; /* find longest string */ left_len = strlen(left->name); right_len = strlen(right->name); if(right_len < left_len) { shortest_string = right_len; } else { shortest_string = left_len; } /* compare strings */ if(strncmp(left->name, right->name, shortest_string) > 1) { return 1; } else if(strncmp(left->name, right->name, shortest_string) < 1) { return -1; } else { /* strings are equal */ if(left->number > right->number) { return 1; } else if(left->number < right->number) { return -1; } else { return 0; } } } And the add method struct Node* _addNode(struct Node* cur, TYPE val) { if(cur == NULL) { /* no root has been made */ cur = _createNode(val); return cur; } else { int cmp; cmp = compare(cur->val, val); if(cmp == -1) { /* go left */ if(cur->left == NULL) { printf("adding on left node val %d\n", cur->val->number); cur->left = _createNode(val); } else { return _addNode(cur->left, val); } } else if(cmp >= 0) { /* go right */ if(cur->rght == NULL) { printf("adding on right node val %d\n", cur->val->number); cur->rght = _createNode(val); } else { return _addNode(cur->rght, val); } } return cur; } } void addBSTree(struct BSTree *tree, TYPE val) { tree->root = _addNode(tree->root, val); tree->cnt++; } The function to print the tree: void printTree(struct Node *cur) { if (cur == 0) { printf("\n"); } else { printf("("); printTree(cur->left); printf(" %s, %d ", cur->val->name, cur->val->number); printTree(cur->rght); printf(")\n"); } } Here's an example of some data that will overwrite previous elements: struct BSTree myTree; struct data myData1, myData2, myData3; myData1.number = 5; myData1.name = "rooty"; myData2.number = 1; myData2.name = "lefty"; myData3.number = 10; myData3.name = "righty"; initBSTree(&myTree); addBSTree(&myTree, &myData1); addBSTree(&myTree, &myData2); addBSTree(&myTree, &myData3); printTree(myTree.root); Which will print: (( righty, 10 ) lefty, 1 ) Finally here's some test data that will go in the exact same spot as the previous data, but this time no data is overwritten: struct BSTree myTree; struct data myData1, myData2, myData3; myData1.number = 5; myData1.name = "i"; myData2.number = 5; myData2.name = "h"; myData3.number = 5; myData3.name = "j"; initBSTree(&myTree); addBSTree(&myTree, &myData1); addBSTree(&myTree, &myData2); addBSTree(&myTree, &myData3); printTree(myTree.root); Which prints: (( j, 5 ) i, 5 ( h, 5 ) ) Does anyone know what might be going wrong? Sorry if this post was kind of long.

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  • Parsing a file with hierarchical structure in Python

    - by Kevin Stargel
    I'm trying to parse the output from a tool into a data structure but I'm having some difficulty getting things right. The file looks like this: Fruits Apple Auxiliary Core Extras Banana Something Coconut Vegetables Eggplant Rutabaga You can see that top-level items are indented by one space, and items beneath that are indented by two spaces for each level. The items are also in alphabetical order. How do I turn the file into a Python list that's something like ["Fruits", "Fruits/Apple", "Fruits/Banana", ..., "Vegetables", "Vegetables/Eggplant", "Vegetables/Rutabaga"]?

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