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Search found 1157 results on 47 pages for 'recursive descent'.

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• Classical Round Table algorithm?

  - by user1795954

  Coins with different value are spread in circle around a round table . We can choose any coin such that for any two adjacent pair of coins , atleast one must be selected (both maybe selected too) . In such condition we have to find minimum possible value of coins selected . I have to respect time complexity so instead of using naive recursive bruteforce , i tried doing it using dynamic programming . But i get Wrong Answer - my algorithm is incorrect . If someone could suggest an algorithm to do it dynamically , i could code myself in c++ . Also maximum number of coins is 10^6 , so i think O(n) solution exists .

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• SICP making change

  - by RyanD

  So; I'm a hobbiest who's trying to work through SICP (it's free!) and there is an example procedure in the first chapter that is meant to count the possible ways to make change with american coins; (change-maker 100) = 292. It's implemented something like: (define (change-maker amount) (define (coin-value n) (cond ((= n 1) 1) ((= n 2) 5) ((= n 3) 10) ((= n 4) 25) ((= n 5) 50))) (define (iter amount coin-type) (cond ((= amount 0) 1) ((or (= coin-type 0) (< amount 0)) 0) (else (+ (iter amount (- coin-type 1)) (iter (- amount (coin-value coin-type)) coin-type))))) (iter amount 5)) Anyway; this is a tree-recursive procedure, and the author "leaves as a challenge" finding an iterative procedure to solve the same problem (ie fixed space). I have not had luck figuring this out or finding an answer after getting frustrated. I'm wondering if it's a brain fart on my part, or if the author's screwing with me.

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• Which cross threading invoke function is better for a control that is inherited?

  - by Stevoni

  I have a relatively simple question regarding the best way to call the DataGridView.Rows.Add function when it is inherited into the current control. Which is the best way to make the call to the inherited control? Call it directly in the invoke or call it using recursive-like function? They both seem to produce the same result, a row gets added and the quantity is returned, but which is the most efficient? The delegate: Private Delegate Function ReturnDelegate() As Object The two ways are: A) Private Overloads Function AddRow() As Integer If InvokeRequired Then Return CInt(Invoke(New ReturnDelegate(AddressOf AddRow))) Else Return Rows.Add() End If End Function Or B) Private Function RowsAdd() As Integer If Me.InvokeRequired Then Return CInt(Me.Invoke(New ReturnDelegate(AddressOf MyBase.Rows.Add))) Else Return MyBase.Rows.Add End If End Function

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• Multidimensional vectors in scheme?

  - by incrediman

  I earlier asked a question about arrays in scheme (turns out they're called vectors but are basically otherwise the same as you'd expect). Is there an easy way to do multidimensional arrays vectors in PLT Scheme though? For my purposes I'd like to have a procedure called make-multid-vector or something. By the way if this doesn't already exist, I don't need a full code example of how to implement it. If I have to roll this myself I'd appreciate some general direction though. The way I'd probably do it is to just iterate through each element of the currently highest dimension of the vector to add another dimension, but I can see that being a bit ugly using scheme's recursive setup. Also, this seems like something I should have been able to find myself so please know that I did actually google it and nothing came up.

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• writing a fast parser in python

  - by panzi

  I've written a hands-on recursive pure python parser for a some file format (ARFF) we use in one lecture. Now running my exercise submission is awfully slow. Turns out by far the most time is spent in my parser. It's consuming a lot of CPU time, the HD is not the bottleneck. I wonder what performant ways are there to write a parser in python? I'd rather not rewrite it in C. I tried to use jython, but that decreased performance a lot! The files I parse are partially huge ( 150 MB) with very long lines. My current parser only needs a look-ahead of one character. I'd post the source here but I don't know if that's such a good idea. After all the submission deadline has not jet ended. But then, the focus in this exercise is not the parser. You can choose whatever language you want to use and there already is a parser for Java.

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• Erlang code critique

  - by dagda1

  Hi, I am trying to get my head round some basic erlang functionality and I could do with some comments on the following. I have the following erlang code that takes a list of tuples and returns a list minus an element if a key is found: delete(Key, Database) -> remove(Database, Key, []). remove([], Key, Acc) -> Acc; remove([H|T], Key, Acc) -> if element(1, H) /= Key -> [H| remove(T, Key, Acc)]; true -> remove(T, Key, Acc) end. Is this a good way of doing this? The if statement seems incorrect. Also is my use of the accumulator Acc making this tail recursive? Cheers Paul

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• python multithread "maximum recursion depth exceed"

  - by user293487

  I use Python multithread to realize Quicksort. Quicksort is implement in a function. It is a recursive function. Each thread calls Quicksort to sort the array it has. Each thread has its own array that stores the numbers needs to be sorted. If the array size is smaller (<10,000). It runs ok. However, if the array size is larger, it shows the "maximum recursion depth exceed". So, I use setrecursionlimit () function to reset the recursion depth to 1500. But the program crash directly...

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• How can I return default at loop end in Scheme?

  - by Kufi Annan

  I'm trying to implement back-tracking search in Scheme. So far, I have the following: (define (backtrack n graph assignment) (cond (assignment-complete n assignment) (assignment) ) (define u (select-u graph assignment)) (define c 1) (define result 0) (let forLoop () (when (valid-choice graph assignment c) (hash-set! assignment u c) (set! result (backtrack n graph assignment)) (cond ((not (eq? result #f)) result)) (hash-remove! assignment u) ) (set! c (+ c 1)) (when (>= n c) (forLoop)) ) #f ) My functions assignment-complete and select-u pass unit tests. The argument assignment is a hash-table make with (make-hash), so it should be fine. I believe the problem I have is related to returning false at the end of the loop, if no recursive returns a non-false value (which should be a valid assignment).

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• adldap class, need to search for user in two groups

  - by Brad

  http://adldap.sourceforge.net/wiki/doku.php?id=api_user_functions#user_ingroup_username_group_recursive_null I am using the adLDAP class above to authenticate users against our ldap server. I was wondering how I could check multiple groups to see if the user belongs to either, if they belong to either. I don't know if user_ingroup($username,$group,$recursive=NULL); can handle search two different groups for the user, need help coding it to search for the user in two different groups, and as soon as it finds it in one of those, break the operation and set a variable to true. Any help is appreciated.

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• fcgio.cpp: In destructor 'virtual fcgi_streambuf::~fcgi_streambuf()':

  - by skyeagle

  I am attempting to build fastcgi on a Linux Ubuntu 10.x machine. I run the following commands: ./configure make and I get the following error: fcgio.cpp: In destructor 'virtual fcgi_streambuf::~fcgi_streambuf()': fcgio.cpp:50: error: 'EOF' was not declared in this scope fcgio.cpp: In member function 'virtual int fcgi_streambuf::overflow(int)': fcgio.cpp:70: error: 'EOF' was not declared in this scope fcgio.cpp:75: error: 'EOF' was not declared in this scope fcgio.cpp: In member function 'virtual int fcgi_streambuf::sync()': fcgio.cpp:86: error: 'EOF' was not declared in this scope fcgio.cpp:87: error: 'EOF' was not declared in this scope fcgio.cpp: In member function 'virtual int fcgi_streambuf::underflow()': fcgio.cpp:107: error: 'EOF' was not declared in this scope make[2]: *** [fcgio.lo] Error 1 make[2]: Leaving directory `/somepath/fcgi-2.4.0/libfcgi' make[1]: *** [all-recursive] Error 1 make[1]: Leaving directory `/somepath/fcgi-2.4.0' make: *** [all] Error 2 I notice that others have had the same problem and have asked this question in various fora etc - however, I have not as yet, seen an answer to this question/problem. Has anyone ever managed to build fastcgi on Linux? How do I fix this problem?

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• HABTM and belongsTo at the same join, cakePhp

  - by Cynthia

  Hello everyone. I have a model Fix with a relationship HABTM Device model. Device model has a belongsTo to Device_type model, like this, for only getting the device type name: var $belongsTo = array('Device_type'=>array('fields'=>'name')); So, I need every Fix, its devices and its Device_types. When I make a Fix->find('all', array('recursive' => 2)) I expect to get every Device related to Fix (this works ok) and ALSO for every device, its Device_type.name (which is not working). This is what I get instead for every Device in the result (an empty array): ["Device_type"]=> array(0) { } Besides this, when I make this query for testing: Fix->Device->find('all'), it returns the current Device_type.names for every device related to fixes, which means models are related propertly. Any help? Thanks.

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• What would be the use of accepting itself as type arguments in generics

  - by Newtopian

  I saw some code on an unrelated question but it got me curious as I never saw such construct with Java Generics. What would be the use of creating a generic class that can take as type argument itself or descendants of itself. Here is example : abstract class A<E extends A> { abstract void foo(E x); } the first thing that came to mind would be a list that takes a list as parameter. Using this code feels strange, how do you declare a variable of type A ? Recursive declaration !? Does this even work ? If so did any of you see that in code ? How was it used ?

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• How to check if a variable is defined in a Master file in ASP.NET MVC

  - by Mortanis

  I've got a Site.Master file I've created to be my template for the majority of the site, with a navigation. This navigation is dynamically created, based on a recursive Entity (called Page) - Pages with a parentID of 0 are top level, and naturally each child carries it's parent's Id in that field. I've created a quick little HTML Helper that accepts the ID of an Page and generates the nav by doing a foreach on the children that have a parentId matching the passed Id. On the majority of the site, I want the Site.Master to use a parentId of 0, but if I'm on a strongly typed View displaying a Page, I naturally want to use the Id of the page. Is there a way to do such conditional logic in a Site.Master (and, does that violate MVC rules)? "If I'm on a strongly typed Page of /Page/{Id}, use the Id render nav, else use 0"

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• too much recursion

  - by Dänu

  Hey guys, I got an error in javascript and it won't get away. :-) In the little recursive thingy following, I want to replace a value inside a (nested) object. var testobj = { 'user': { 'name': 'Mario', 'password': 'itseme' } }; updateObject('emesti', 'password', testobj) function updateObject(_value, _property, _object) { for(var property in _object) { if(property == _property) { _object[property] = _value; } else if(objectSize(_object) > 0) { updateObject(_value, _property, _object[property]); } } return _object }; function objectSize(_object) { var size = 0, key; for (key in _object) { if (_object.hasOwnProperty(key)) size++; } return size; }; After running this, firefox throws the exception "too much recursion" on the line else if(objectSize(_object) > 0) { .

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• How do I write a constant-space length function in Haskell?

  - by Bill

  The canonical implementation of length :: [a] -> Int is: length [] = 0 length (x:xs) = 1 + length xs which is very beautiful but suffers from stack overflow as it uses linear space. The tail-recursive version: length xs = length' xs 0 where length' [] n = n length' (x:xs) n = length xs (n + 1) doesn't suffer from this problem, but I don't understand how this can run in constant space in a lazy language. Isn't the runtime accumulating numerous (n + 1) thunks as it moves through the list? Shouldn't this function Haskell to consume O(n) space and lead to stack overflow? (if it matters, I'm using GHC)

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• Is it possible to have a Ocaml function that accepts only integer lists?

  - by Sam

  I'm writing a recursive function in Ocaml that's supposed to count the number of items in an integer list (Yes I know there's a List.length function but I'm trying to do it myself). However the Ocaml compiler/interpreter forces me to use alpha list all the time. So is it wrong to say that, when a function accepts a list as a parameter, the type of that list must always be alpha? Thanks EDIT: the reason why it's inconvenient for me to use alpha lists is because i can't compare the head of the alpha list with an integer value due to type-matching complaints

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• Cleanest way to tell if 3 times are within half an hour of each other

  - by niggles

  I have 3 date / time input boxes on a form and the user cannot select any times within half an hour of each other. I've converted all values to epoch format using a Javascript implementation of strtotime, but not sure how to recursively check that any of the times are actually half an hour apart. I can hand code all checks, but it would be cleaner to write a recursive function (especially if there were theoretically more than 3 time slots). Did some Google research but no luck. Any suggestions on implementing this in Javascript or Jquery. Thanks.

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• Entity Framework associations killing performance

  - by Chris

  Here is the performance test i am looking at. I have 8 different entities that are table per type. Some of the entities contain over 100 thousand rows. This particular application does several recursive calculations on the client so I think it may be best to preload the data instead of lazy loading. If there are no associations I can load the entire database in about 3 seconds. As I add associations in any way the performance starts to drastically decline. I am loading all the data the same way (just calling toList() on the entity attached to the context). I ran the test with edmx generated classes and self tracking entities and had similar results. I am sure if I were to try and deal with the associations myself, similar to how I would in a dataset, the performance problem would go away. On the other hand I am pretty sure this is not how the entity framework was intended to being used. Any thoughts or ideas?

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• Waiting on multiple asynchronous calls to complete before continuing

  - by Chad

  So, I have a page that loads and through jquery.get makes several requests to populate drop downs with their values. $(function() { LoadCategories($('#Category')); LoadPositions($('#Position')); LoadDepartments($('#Department')); LoadContact(); }; It then calls LoadContact(); Which does another call, and when it returns it populates all the fields on the form. The problem is that often, the dropdowns aren't all populated, and thus, it can't set them to the correct value. What I need to be able to do, is somehow have LoadContact only execute once the other methods are complete and callbacks done executing. But, I don't want to have to put a bunch of flags in the end of the drop down population callbacks, that I then check, and have to have a recursive setTimeout call checking, prior to calling LoadContact(); Is there something in jQuery that allows me to say, "Execute this, when all of these are done."?

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• Multilevel nested product categories display with asp.net and sql server?

  - by Kunal

  I have a product category table with the following fields: cat_id (PK) Cat_name Cat_desc Parent_Cat_Id Now when a user wants to add a product he should be able to select multiple categories from a listbox(multiselection enabaled). But to let the user know the hierarchy of the categories, I need to display them in the following style: parent category 1 parent category 1-sub category 1 parent category 1-sub category 1-sub-sub category 1 parent category 1-sub category 1-sub-sub category 2 parent category 1-sub category 2 Parent category 2 ... I know that to achieve this I need to use recursive programming. But how can we do it via stored procedures? That would be much more efficient, right? Thanks in advance for your kind help.

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• How to evaluate a custom math expression in Python

  - by taynaron

  I'm writing a custom dice rolling parser (snicker if you must) in python. Basically, I want to use standard math evaluation but add the 'd' operator: #xdy sum = 0 for each in range(x): sum += randInt(1, y) return sum So that, for example, 1d6+2d6+2d6-72+4d100 = (5)+(1+1)+(6+2)-72+(5+39+38+59) = 84 I was using regex to replace all 'd's with the sum and then using eval, but my regex fell apart when dealing with parentheses on either side. Is there a faster way to go about this than implementing my own recursive parsing? Perhaps adding an operator to eval?

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• Dynamically set generic type argument

  - by fearofawhackplanet

  Following on from my question here, I'm trying to create a generic value equality comparer. I've never played with reflection before so not sure if I'm on the right track, but anyway I've got this idea so far: bool ContainSameValues<T>(T t1, T t2) { if (t1 is ValueType || t1 is string) { return t1.Equals(t2); } else { IEnumerable<PropertyInfo> properties = t1.GetType().GetProperties().Where(p => p.CanRead); foreach (var property in properties) { var p1 = property.GetValue(t1, null); var p2 = property.GetValue(t2, null); if( !ContainSameValues<p1.GetType()>(p1, p2) ) return false; } } return true; } This doesn't compile because I can't work out how to set the type of T in the recursive call. Is it possible to do this dynamically at all? There are a couple of related questions on here which I have read but I couldn't follow them enough to work out how they might apply in my situation.

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• Web-based JSON editor that works like property explorer with AJAXy input form

  - by dreftymac

  Background: This is a request for something that may not exist yet, but I've been meaning to build one for a long time. First I will ask if anyone has seen anything like it yet. Suppose you have an arbitrary JSON structure like the following: { 'str_title':'My Employee List' ,'str_lastmod': '2009-June-15' ,'arr_list':[ {'firstname':'john','lastname':'doe','age':'33',} ,{'firstname':'jane','lastname':'doe','age':'34',} ,{'firstname':'samuel','lastname':'doe','age':'35',} ] } Question: Is there a web-based JSON editor that could take a structure like this, and automatically allow the user to modify this in a user-friendly GUI? Example: Imagine an auto-generated HTML form that displays 2 input-type-text controls for both title and lastmod, and a table of input-type-text controls with three columns and three rows for arr_list ... with the ability to delete or add additional rows by clicking on a [+][X] next to each row in the table. Big Idea: The "big idea" behind this is that the user would be able to specify any arbitrary (non-recursive) JSON structure and then also be able to edit the structure with a GUI-based interaction (this would be similar to the "XML Editor Grid View" in XML Spy).

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• What's the best way to measure and track performance over various calls at runtime?

  - by bitcruncher

  Hello. I'm trying to optimize the performance of my code, but I'm not familiar with xcode's debuggers or debuggers in general. Is it possible to track the execution time and frequency of calls being made at runtime? Imagine a chain of events with some recursive calls over a fraction of a second. What's the best way to track where the CPU spends most of its time? Many thanks. Edit: Maybe this is better asked by saying, how do I use the xcode debug tools to do a stack trace?

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• Is it magic or what ??

  - by STRIDER

  I am writing a big C code... The code includes recursive bactracking function named Branch() that is called so much... My goal is to write the fastest code to get the best running time... I also have another function Redundant() void Redundant() { int* A; A=(int*)malloc(100*sizeof(int)); } I created two versions. Version A: Redundant() is included in Branch(). Version B: Redundant() is not included in Branch() A run 10 times faster than B !!!! Is is Magic or is it kind of process scheduling or what ??

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