questions about recursion

Examples of Recursive functions

Can anybody suggest programming examples that illustrate recursive functions? There are the usual old horses such as Fibonacci series and Towers of Hanoi, but anything besides them would be fun. ...

recursion

How do I write a generic memoize function?

I'm writing a function to find triangle numbers and the natural way to write it is recursively: function triangle (x) if x == 0 then return 0 end return x+triangle(x-1) end But attempting to calculate the first 100,000 triangle numbers fails with a stack overflow after a while. This is an ideal function to memoize, but I want a...

Faster Directory Walk with VB6 Query: Cache and Ram issues?

Below is a rather simple function which counts how many files are on a machine. Called on "C:\", it takes about 5 seconds to run. Unless I haven't run it in a while or first run a ram-clearing program, in which case it takes 60 seconds or more. I wouldn't have thought it could be caching since I'm doing a new scan each time (i.e. star...

Recursive List Flattening

I could probably write this myself, but the specific way I'm trying to accomplish it is throwing me off. I'm trying to write a generic extension method similar to the others introduced in .NET 3.5 that will take a nested IEnumerable of IEnumerables (and so on) and flatten it into one IEnumerable. Anyone have any ideas? Specifically, I...

c#

.net

recursion

Which languages support recursive function literals / anonymous functions?

It seems quite a few mainstream languages support function literals these days. They are also called anonymous functions, but I don't care if they have a name. The important thing is that a function literal is an expression which yields a function which hasn't already been defined elsewhere, so for example in C, &printf doesn't count. E...

Way to go from recursion to iteration

I've used recursion quite a lot on my many years of programming to solve simple problems, but I'm fully aware that sometimes you need iteration due to memory/speed problems. So, sometime in the very far past I went to try and find if there existed any "pattern" or text-book way of transforming a common recursion approach to iteration an...

Should I use threading and recursion together?

I have been tinkering with BSP trees for a while now and am also playing with threads. When adding a triangle to a BSP tree, an opportunity arises to create a new thread for the purposes of processing data in parallel. insert(triangle, bspnode) { .... else if(triangle spans bspnode) { (frontpiece, backpiece) = plane_split(tr...

multithreading

recursion

What's the best way to find a string/regex match in files recursively? (UNIX)

I have had to do this several times, usually when trying to find in what files a variable or a function is used. I remember using xargs with grep in the past to do this, but I am wondering if there are any easier ways. ...

Is recursion good in SQL Server?

I have a table in SQL server that has the normal tree structure of Item_ID, Item_ParentID. Suppose I want to iterate and get all CHILDREN of a particular Item_ID (at any level). Recursion seems an intuitive candidate for this problem and I can write an SQL Server function to do this. Will this affect performance if my table has many m...

sql-server

recursion

What is the most efficient/elegant way to parse a flat table into a tree?

Assume you have a flat table that stores an ordered tree hierarchy: Id Name ParentId Order 1 'Node 1' 0 10 2 'Node 1.1' 1 10 3 'Node 2' 0 20 4 'Node 1.1.1' 2 10 5 'Node 2.1' 3 10 6 'Node 1.2' 1 20 What minimalistic appro...

Recursion and Big O

I've been working through a recent Computer Science homework involving recursion and big-O notation. I believe I understand this pretty well (certainly not perfectly, though!) But there is one question in particular that is giving me the most problems. The odd thing is that by looking it, it looks to be the most simple one on the homewor...

recursion instead of multi-loops

I want this method to work for any given number of arguments, i can do that with code generation(with a lot of ugly code), can it be done with recursion? if so how? I understand recursion, but i dont know how to write this. private static void allCombinations(List<String>... lists) { if (lists.length == 3) { for (String s3 : lists[0]...

can i clean stacktrace?

i know that i can get stacktrace by using Thread.getAllStackTraces()(it returns Map, but clear does not work). When I run recursion method i can get exception because of stacktrace being too big, is there any way to clear it? ...

java

recursion

Parsing of nested tags in a file

Hi, I am wondering - What's the most effective way of parsing something like: {{HEADER}} Hello my name is {{NAME}} {{#CONTENT}} This is the content ... {{#PERSONS}} <p>My name is {{NAME}}.</p> {{/PERSONS}} {{/CONTENT}} {{FOOTER}} Of course this is intended to be somewhat of a templating system in the end, s...

How do I reverse a list using recursion in Python?

I want to have a function that will return the reverse of a list that it is given -- using recursion. How can I do that? ...

How do I use Master theorem to describe recursion?

Recently I have been studying recursion; how to write it, analyze it, etc. I have thought for a while that recurrence and recursion were the same thing, but some problems on recent homework assignments and quizzes have me thinking there are slight differences, that 'recurrence' is the way to describe a recursive program or function. Thi...

homework

recursion

recurrence

How can I copy a directory recursively and filter filenames in Perl?

How do I copy a directory including sub directories excluding files or directories that match a certain regex on a Windows system? ...

perl

recursion

Summing up all nodes

This may be a simple fix - but I'm trying to sum together all the nodes (Size property from the Node class) on the binary search tree. Below in my BST class I have the following so far, but it returns 0: private long sum(Node<T> thisNode) { if (thisNode.Left == null && thisNode.Right == null) return 0; ...