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  • Updating a Minimum spanning tree when a new edge is inserted

    - by Lynette
    Hello, I've been presented the following problem in University: Let G = (V, E) be an (undirected) graph with costs ce = 0 on the edges e € E. Assume you are given a minimum-cost spanning tree T in G. Now assume that a new edge is added to G, connecting two nodes v, tv € V with cost c. a) Give an efficient algorithm to test if T remains the minimum-cost spanning tree with the new edge added to G (but not to the tree T). Make your algorithm run in time O(|E|). Can you do it in O(|V|) time? Please note any assumptions you make about what data structure is used to represent the tree T and the graph G. b)Suppose T is no longer the minimum-cost spanning tree. Give a linear-time algorithm (time O(|E|)) to update the tree T to the new minimum-cost spanning tree. This is the solution I found: Let e1=(a,b) the new edge added Find in T the shortest path from a to b (BFS) if e1 is the most expensive edge in the cycle then T remains the MST else T is not the MST It seems to work but i can easily make this run in O(|V|) time, while the problem asks O(|E|) time. Am i missing something? By the way we are authorized to ask for help from anyone so I'm not cheating :D Thanks in advance

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  • Display a tree dijit using zend framework

    - by churris43
    I am trying to display a tree of categories and subcategories by using dijits with zend framework. Haven't been able to find a good example. This is what I've got: Basically I got the following code as my action: class SubcategoriesController extends Zend_Controller_Action{ ..... public function loadtreeAction() { Zend_Dojo::enableView($this->view); Zend_Layout::getMvcInstance()->disableLayout(); //Creating a sample tree of categories and subcategories $a["cat1"]["id"] = "id1"; $a["cat1"]["name"] = "Category1"; $a["cat1"]["type"] = "category"; $subcat1 = array("id" => "Subcat1","name" => "Subcategory1" , "type" => "subcategory"); $subcat2 = array("id" => "Subcat12","name" => "Subcategory12" , "type" => "subcategory"); $a["cat1"]["children"] = array($subcat1,$subcat2); $treeObj = new Zend_Dojo_Data('id', $a); $treeObj->setLabel('name'); $this->view->tree = $treeObj->toJson(); } .... } And on my view: <?php $this->dojo()->requireModule('dojo.data.ItemFileReadStore'); $this->dojo()->requireModule('dijit.Tree'); $this->dojo()->requireModule('dojo.parser'); ?> <div dojoType="dojo.data.ItemFileReadStore" url="/Subcategories/loadtree" jsId="store"></div> <div dojoType="dijit.tree.ForestStoreModel" jsId="treeModel" store="store" rootId="root" rootLabel="List of Categories" childrenAttrs="children" query="{type:'category'}"></div> <div dojoType="dijit.Tree" model="treeModel" labelAttrs="ListOfCategories"></div> It doesn't even seem to try to load the tree at all. Any help is appreciated

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  • What makes you look like a bad developer (ie a hacker) [on hold]

    - by user134583
    This comes from a lot of people about me, so I have to look at myself. So I would wonder what make one a bad developer (ie a hacker). These are a few things about me I used IDE intensively, all features, you name it: auto-completion, refactoring, quick fixes, open type, view hierarchy, API documentation, etcc When I deal with writing code for a project in domain I am not used to (I can't have fluency in this, this is new), I only have a very rough high level ideas. I don't use the standard modeling diagrams for early detail planning. Unorthodox diagrams that I invented when I need to draw the design in details. I don't use UML or similar, I find them not enough. I divide the sorts of diagram I drew into 3 types. Very high level diagrams which probably can be understood by almost anybody. Data entity diagram used for modeling data objects only (like ER diagrams and tree for inheritances and composition). Action diagrams for agents/classes and their interactions on data objects they contain. Constantly changing the interface (public methods) between interacting agents/classes if the need arises. I am more refrained when the interface and the module have matured Write initial concept code in a quick hackie way just so that the module works in the general cases so that I can play around with it. The module will be re-factored intensively after playing around so I could see more corner cases that I couldn't or (wouldn't want) anticipate before writing code. Using JUnit for integration-like test by using TestSuite class and ordering Unit test classes in the suite Using debugger almost anytime there is a problem instead of reading the code Constantly search on the internet for how to do some thing with some library that I haven't used a lot. So judgment, am I a bad developer? a hacker? Put in other words, to make sure this is not considered off-topic: - Is this bad practice to make your code too agile during incubating/prototyping phase of software development - Is it bad practice to use JUnit for integration testing, (I know there are other framework for integration testing, but those frameworks are for a specific products, not general)

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  • Reduced Tree View in NetBeans IDE 7.2

    - by Geertjan
    Right-click within the Projects window in NetBeans IDE 7.2 and from the "View Java Packages As" menu, you can now choose "Reduced Tree".I never really understood the difference between "Reduced Tree" and the already existing "Tree". But it makes sense when you see it. Here's Reduced Tree view: And here's Tree view, where you can see that the "actions" and "nodes" packages above each have their own top level package nodes, which takes up more space than the above: What's cool is that your selected package view is persisted across restarts of the IDE. To be complete, here's the List view, which is the third option you have in the "View Java Packages As" menu: Seems to me like the new Reduced Tree view combines the best of the Tree view with the best of the List view! Related issue: http://netbeans.org/bugzilla/show_bug.cgi?id=53192

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  • check if a tree is a binary search tree

    - by TimeToCodeTheRoad
    I have written the following code to check if a tree is a Binary search tree. Please help me check the code: Pair p{ boolean isTrue; int min; int max; } public boo lean isBst(BNode v){ return isBST1(v).isTrue; } public Pair isBST1(BNode v){ if(v==null) return new Pair(true, INTEGER.MIN,INTEGER.MAX); if(v.left==null && v.right==null) return new Pair(true, v.data, v.data); Pair pLeft=isBST1(v.left); Pair pRight=isBST1(v.right); boolean check=pLeft.max<v.data && v.data<= pRight.min; Pair p=new Pair(); p.isTrue=check&&pLeft.isTrue&&pRight.isTrue; p.min=pLeft.min; p.max=pRight.max; return p; } Note: This function checks if a tree is a binary search tree

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  • how does NTFS actually work with B-tree ?

    - by bakra
    To improve performance, NTFS directories use a special data management structure called a B-tree. "B-tree" concept here refers to a "tree of storage units" that hold the contents of an individual directory. What I don't understand is where on the disk is this tree stored? Its surely not created every-time we reboot...that would take lots of time. and since its a tree(dynamic Data structure) unlike arrays it will grow. so space needs to be allocated every-time it grows. so how is this "dynamic meta-data" stored ?

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  • Accessing selected node of richfaces tree from Javascript

    - by kazanaki
    Hello This should be a very simple question. I have a richfaces tree that is rendered using JSF. When the user clicks on a node I want a javascript function to run. Nothing more nothing less. No redirects, no re-submit, no-rerender, no Ajax. Just plain old Javascript. I have seen the onselected attribute of the tree and it indeed fires a Javascript method. But of course I want to know which node was clicked. Here is what I have so far <head> <script type="text/javascript"> function documentClicked(nodeRef) { alert("Node is "+nodeRef); } </script> </head> <rich:tree switchType="client" value="#{ajaxDocumentTree.rootNode}" var="document" onselected="documentClicked()" > <rich:treeNode iconLeaf="../images/tree/doc.gif" icon="../images/tree/doc.gif"> <h:outputText value="#{doc.friendlyName}" /> </rich:treeNode> But this does not work because nodeRef is undefined. I expected that the first argument of the callback would be the selected node but this is not the case. So the question is this: How do I fire a Javascript function with the selected node from a richfaces tree?

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  • JQGrid tree - passing additional parameters when tree is expanded

    - by PHP thinker
    I have a JQGRid tree. It loads data click by click, not all at once. Typically, JQGRid passes 4 standard tree parameters with each call - row (level, parent, is leaf, is expanded). How can I pass more parameters that I will take from the row being expanded? E.g. data from Name column should be passed in AJAX call too. There doesn't seem to be OnExpand event or similar.

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  • k-d tree implementation [closed]

    - by user466441
    when i run my code and debugged,i got this error - this 0x00093584 {_Myproxy=0x00000000 _Mynextiter=0x00000000 } std::_Iterator_base12 * const - _Myproxy 0x00000000 {_Mycont=??? _Myfirstiter=??? } std::_Container_proxy * _Mycont CXX0017: Error: symbol "" not found _Myfirstiter CXX0030: Error: expression cannot be evaluated + _Mynextiter 0x00000000 {_Myproxy=??? _Mynextiter=??? } std::_Iterator_base12 * but i dont know what does it means,code is this #include<iostream> #include<vector> #include<algorithm> using namespace std; struct point { float x,y; }; vector<point>pointleft(4); vector<point>pointright(4); //we are going to implement two comparison function for x and y coordinates,we need it in calculation of median (we should sort vector //by x or y according to depth informaton,is depth even or odd. bool sortby_X(point &a,point &b) { return a.x<b.x; } bool sortby_Y(point &a,point &b) { return a.y<b.y; } //so i am going to implement to median finding algorithm,one for finding median by x and another find median by y point medianx(vector<point>points) { point temp; sort(points.begin(),points.end(),sortby_X); temp=points[(points.size()/2)]; return temp; } point mediany(vector<point>points) { point temp; sort(points.begin(),points.end(),sortby_Y); temp=points[(points.size()/2)]; return temp; } //now construct basic tree structure struct Tree { float x,y; Tree(point a) { x=a.x; y=a.y; } Tree *left; Tree *right; }; Tree * build_kd( Tree *root,vector<point>points,int depth) { point temp; if(points.size()==1)// that point is as a leaf { if(root==NULL) root=new Tree(points[0]); return root; } if(depth%2==0) { temp=medianx(points); root=new Tree(temp); for(int i=0;i<points.size();i++) { if (points[i].x<temp.x) pointleft[i]=points[i]; else pointright[i]=points[i]; } } else { temp=mediany(points); root=new Tree(temp); for(int i=0;i<points.size();i++) { if(points[i].y<temp.y) pointleft[i]=points[i]; else pointright[i]=points[i]; } } return build_kd(root->left,pointleft,depth+1); return build_kd(root->right,pointright,depth+1); } void print(Tree *root) { while(root!=NULL) { cout<<root->x<<" " <<root->y; print(root->left); print(root->right); } } int main() { int depth=0; Tree *root=NULL; vector<point>points(4); float x,y; int n=4; for(int i=0;i<n;i++) { cin>>x>>y; points[i].x=x; points[i].y=y; } root=build_kd(root,points,depth); print(root); return 0; } i am trying ti implement in c++ this pseudo code tuple function build_kd_tree(int depth, set points): if points contains only one point: return that point as a leaf. if depth is even: Calculate the median x-value. Create a set of points (pointsLeft) that have x-values less than the median. Create a set of points (pointsRight) that have x-values greater than or equal to the median. else: Calculate the median y-value. Create a set of points (pointsLeft) that have y-values less than the median. Create a set of points (pointsRight) that have y-values greater than or equal to the median. treeLeft = build_kd_tree(depth + 1, pointsLeft) treeRight = build_kd_tree(depth + 1, pointsRight) return(median, treeLeft, treeRight) please help me what this error means?

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  • Extjs: Tree, Selecting node after creating the tree

    - by Natkeeran
    I have a simple TreePanel. I would like to select a particular node upon loading it. The nodes are from a remote file (json). The tree is loading as expected. However, the node is not being selected. Firebug shows node as undefined. This perhaps because of the async property. But, I an unable to configure this other wise, or specify the node be selected. Any suggestions welcomed, and thank you. LeftMenuTree = new Ext.tree.TreePanel({ renderTo: 'TreeMenu', collapsible: false, height: 450, border: false, userArrows: true, animate: true, autoScroll: true, id: 'testtest', dataUrl: fileName, root: { nodeType: 'async', iconCls:'home-icon', expanded:true, text: rootText }, listeners: { "click": { fn: onPoseClick, scope: this } }, "afterrender": { fn: setNode, scope: this } }); function setNode(){ alert (SelectedNode); if (SelectedNode == "Orders"){ var treepanel = Ext.getCmp('testtest'); var node = treepanel.getNodeById("PendingItems"); node.select(); } }

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  • SVN project folder tree structure vs production folder tree structure

    - by Marco Demaio
    While developing a PHP+JS web application we always try to separate big blocks of code into small modules/components, in order to make these last ones as much reusable as possible in other applications. Let's say we now have: the EcommerceApp (an ecommerce main application) a Server-file-mgr component (a component to view/manage file on server) a Mylib (a library of useful functions) a MailistApp (another main application to handle mail lists) ... EcommerceApp needs both Server-file-mgr component and Mylib to work Server-file-mgr needs Mylib to work MaillistApp needs both Server-file-mgr component and Mylib to work too. My idea is to simply structure the SVN project folder tree putting everything at the same level: trunk/EcommerceApp trunk/Server-file-mgr trunk/Mylib trunk/MaillistApp But in real life to make these apps to work the folder tree structure must be the following: EcommerceApp |_ Mylib |_ Server-file-mgr MaillistApp |_ Mylib |_ Server-file-mgr I mean Mylib and Server-file-mgr needs to be inside the EcommerceApp/MaillistApp folder. How would you then structure the SVN folder, as I did or in a different/better/smarter way???

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  • Insert element into a tree from a list in Standard ML

    - by vichet
    I have just started to learn SML on my own and get stuck with a question from the tutorial. Let say I have: tree data type datatype node of (tree*int*tree) | null insert function fun insert (newItem, null) = node (null, newItem, null) | insert (newItem, node (left, oldItem, right)) = if (newItem <= oldItem) then node (insert(newItem,left),oldItem, right) else node (left, oldItem, insert(newItem, right) an integer list val intList = [19,23,21,100,2]; my question is how can I add write a function to loop through each element in the list and add to a tree? Your answer is really appreciated.

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  • Maximum depth of a B-tree

    - by Phenom
    How do you figure out the maximum depth of a B-tree? Say you had a B-tree of order 1625, meaning each node has 1625 pointers and 1624 elements. What is the maximum depth of the tree if it contains 85,000,000 keys?

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  • Family Tree :- myheritage.com

    - by Nitesh Panchal
    Hello, The other day i just accidently visited the site myheritage.com. I was just wondering, how they must have created one? Can anybody tell me what can be their database design? and if possible, algorithm that we can use to generate such a tree? Generating simple binary tree is very easy using recursion. But if you have a look at the site(if you have time please make account on it and add few nodes to feel) when we add son to a father, it's mother is automatically added(if you don't add explicitly). Mother's family tree is also generated side by side and many such fancy things are happening. In a simple binary tree we have a root node and then many nodes below it. Thus we cannot show wife and husband in the tree and then show a line from wife and husband to child. In spare time, can anybody discuss what can be it's database design and the recursive algorithm that we can follow to generate it? I hope i am not asking too much from you :).

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  • Sorting by custom field and fetching whole tree from DB

    - by Niaxon
    Hello everyone, I am trying to do file browser in a tree form and have a problem to sort it somehow. I use PHP and MySQL for that. I've created mixed (nested set + adjacency) table 'element' with the following fields: element_id, left_key, right_key, level, parent_id, element_name, element_type (enum: 'folder','file'), element_size. Let's not discuss right now that it is better to move information about element (name, type, size) into other table. Function to scan specified directory and fill table work correctly. Noteworthy, i am adding elements to tree in specific order: folders first and then files. After that i can easily fetch and display whole table on the page using simple query: SELECT * FROM element WHERE 1=1 ORDER BY left_key With the result of that query and another function i can generate correct html code (<ul><li>... and so on). to display tree. Now back to the question (finally, huh?). I am struggling to add sorting functionality. For example i want to order my result by size. Here i need to keep in my mind whole hierarchy of tree and rule: folders first, files later. I believe i can do that by generating in PHP recursive query: SELECT * FROM element WHERE parent_id = {$parentId} ORDER BY element_type (so folders would be first), size (or name for example) asc/desc After that for each result which has type = 'folder' i will send another query to get it's content. Also it's possible to fetch whole tree by left_key and after that sort it in PHP as array but i guess that would be worse :) I wonder if there is better and more efficient way to do such a thing?

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  • How to Populate a 'Tree' structure 'Declaratively'

    - by mackenir
    I want to define a 'node' class/struct and then declare a tree of these nodes in code in such a way that the way the code is formatted reflects the tree structure, and there's not 'too much' boiler plate in the way. Note that this isn't a question about data structures, but rather about what features of C++ I could use to arrive at a similar style of declarative code to the example below. Possibly with C++0X this would be easier as it has more capabilities in the area of constructing objects and collections, but I'm using Visual Studio 2008. Example tree node type: struct node { string name; node* children; node(const char* name, node* children); node(const char* name); }; What I want to do: Declare a tree so its structure is reflected in the source code node root = node("foo", [ node("child1"), node("child2", [ node("grand_child1"), node("grand_child2"), node("grand_child3" ]), node("child3") ]); NB: what I don't want to do: Declare a whole bunch of temporary objects/colls and construct the tree 'backwards' node grandkids[] = node[3] { node("grand_child1"), node("grand_child2"), node("grand_child3" }; node kids[] = node[3] { node("child1"), node("child2", grandkids) node("child3") }; node root = node("foo", kids);

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  • unique substrings using suffix tree

    - by user1708762
    For a given string S of length n- Optimal algorithm for finding all unique substrings of S can't be less than O(n^2). So, the best algorithm will give us the complexity of O(n^2). As per what I have read, this can be implemented by creating suffix tree for S. The suffix tree for S can be created in O(n) time. Now, my question is- How can we use the suffix tree for S to get all the unique substrings of S in O(n^2)?

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  • Help A Hacker: Give ‘Em The Windows Source Code

    - by Ken Cox [MVP]
    The announcement of another Windows megapatch reminded me of a WikiLeaks story about Microsoft Windows that hasn’t attracted much attention. Alarmingly, we learn that the hackers have the Windows source code to study and test for vulnerabilities. Chinese hackers used the knowledge to breach Google’s accounts and servers: “In 2003, the CNITSEC signed a Government Security Program (GSP) international agreement with Microsoft that allowed select companies such as TOPSEC access to Microsoft source code in order to secure the Windows platform” “CNITSEC enterprises has recruited Chinese hackers in support of nationally-funded "network attack scientific research projects." From June 2002 to March 2003, TOPSEC employed a known Chinese hacker, Lin Yong (a.k.a. Lion and owner of the Honker Union of China), as senior security service engineer…” Windows is widely seen as unsecurable. It doesn’t help that Chinese government-funded hackers are probing the source code for vulnerabilities. It seems odd that people who didn’t write the code can find vulnerabilities faster than the owners of the code. Perhaps the U.S. government should hire its own hackers to go over the same Windows source code and then tell Microsoft how to secure its product?

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