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Sorting Algorithm Animations
These pages show 8 different sorting algorithms on 4 different initial conditions. These visualizations are intended to:

Show how each algorithm operates.
Show that there is no best sorting algorithm.
Show the advantages and disadvantages of each algorithm.
Show that worse-case asymptotic behavior is not always the deciding factor in choosing an algorithm.
Show that the initial condition (input order and key distribution) affects performance as much as the algorithm choice.
algorithm  programming  gif  animated  geek  reference  sorting 
july 2015 by rtopitt
Top 10 data mining algorithms in plain English |
Today, I’m going to explain in plain English the top 10 most influential data mining algorithms as voted on by 3 separate panels in this survey paper.

Once you know what they are, how they work, what they do and where you can find them, my hope is you’ll have this blog post as a springboard to learn even more about data mining.
ai  algorithm  data  data_mining  top10  geek  programming  reference  machine_learning 
june 2015 by rtopitt
Enough With the Salts: Updates on Secure Password Schemes - Blog - Matasano Security
When it comes to password storage, you’re much better off using a well tested and reviewed system than writing your own. You’ll want that to be something purpose built, rather than relying on fast cryptographic hashes which are especially susceptible to fast guessing and hardware optimization. This means you’ll want to use scrypt, bcrypt, or PBKDF2 (in my order of preference) with an appropriate work factor. If you’re stuck deciding between scrypt and bcrypt, you can pretty much flip a coin and end up with something reasonable.
hash  security  senha  criptografia  server  database  boa_prática  reference  importante  algorithm 
april 2015 by rtopitt
VisuAlgo - visualising data structures and algorithms through animation
VisuAlgo was conceptualised in 2011 by Dr Steven Halim as a tool to help his students better understand data structures and algorithms, by allowing them to learn the basics on their own and at their own pace.
interactive  algorithm  programming  gráfico  visualização  geek 
september 2014 by rtopitt
Collaborative Filtering With Likes and Dislikes -
I want to talk about an algorithm I don’t see used often but would work great for my other friends, Like and Dislike. I want to talk about the Jaccard similarity coefficient! The Jaccard index is a simple calculation of similarity between sample sets.
similaridade  blog  ruby  machine_learning  inspiração  algorithm  tip  recomendation 
may 2013 by rtopitt
Big-O Algorithm Complexity Cheat Sheet
This webpage covers the space and time Big-O complexities of common algorithms used in Computer Science.
cs  complexidade  cheat_sheet  tabela  comparação  reference  algorithm  programming 
may 2013 by rtopitt
Array Iteration Interview Problem : jazzychad's blog
Over the past year, I have interviewed several cadidates for programming positions at tech startups. The following problem is a variation of a question I have asked in each of those interviews. I say that the candidate can use any language they choose, and most use ruby.
entrevista  teste  lógica  ruby  javascript  inspiração  importante  pergunta  array  algorithm  programming 
august 2012 by rtopitt
Project Euler
Project Euler is a series of challenging mathematical/computer programming problems that will require more than just mathematical insights to solve. Although mathematics will help you arrive at elegant and efficient methods, the use of a computer and programming skills will be required to solve most problems.

The motivation for starting Project Euler, and its continuation, is to provide a platform for the inquiring mind to delve into unfamiliar areas and learn new concepts in a fun and recreational context.
teste  problema  exercício  matemática  algorithm  programming 
april 2012 by rtopitt
Clever Algorithms
The book "Clever Algorithms: Nature-Inspired Programming Recipes" by Jason Brownlee PhD describes 45 algorithms from the the field of Artificial Intelligence. All algorithm descriptions are complete and consistent to ensure that they are accessible, usable and understandable by a wide audience. 45 algorithms described. Designed specifically for Programmers, Research Scientists and Interested Amateurs. Complete code examples in the Ruby programming language. Standardized algorithm descriptions. Algorithms drawn from the popular fields of Computational Intelligence, Metahuristics, and Biologically Inspired Computation.
ruby  ia  inteligência_artificial  livro  pdf  grátis  download  e-book  algorithm  programming 
january 2011 by rtopitt
How Shazam Works « Free Won’t
I was curious how it worked, and luckily there is a paper written by one of the developers explaining just that. Of course they leave out some of the details, but the basic idea is exactly what you would expect: it relies on fingerprinting music based on the spectrogram.
shazam  geek  frequência  espectro  how-to  explicação  música  som  algorithm 
september 2010 by rtopitt
Auto Complete with Redis
Auto complete is a cool and useful feature for users, but it can be non trivial to implement it with good performances when the set of completions is big.
autocomplete  how-to  redis  ruby  geek  busca  algorithm  programming 
september 2010 by rtopitt
why GNU grep is fast
Here's a quick summary of where GNU grep gets
its speed. #1 trick: GNU grep is fast because it AVOIDS LOOKING AT
EVERY INPUT BYTE. #2 trick: GNU grep is fast because it EXECUTES VERY FEW INSTRUCTIONS FOR EACH BYTE that it *does* look at.
grep  gnu  linux  performance  unix  busca  string  algorithm  programming 
august 2010 by rtopitt
The Britney Spears Problem » American Scientist
Tracking who's hot and who's not presents an algorithmic challenge.
geek  trend  trending  artigo  inspiração  algorithm  science  programming 
august 2010 by rtopitt
Achievements Unlocked | Xbox Engineering Blog |
The Xbox Engineering blog recently posted a glimpse into the creation of the Xbox 360 achievement system, discussing how achievements work at a software level, and even showing a brief snippet of code. They also mention some of the decisions they struggled with while creating them.
xbox  xbox_360  360  achievements  história  videogame  inspiração  badge  game_mechanics  importante  review  decisão  algorithm  programming 
july 2010 by rtopitt
Finding Similarities - Oscar Del Ben
Versões em Ruby dos algoritmos de similaridade e recomendação do Programming Collective Intelligence.
ruby  livro  web2.0  importante  riopro  algorithm  programming 
june 2010 by rtopitt
How I Built a Working Poker Bot, Part 1
Several years ago, a client asked me to come up with a prototype for a real-money online poker bot. That's right: a piece of software you park on your computer while it goes out to a site like PokerStars or Full Tilt and plays no-limit Holdem for you, at 4 or 14 different tables, for real-money stakes. Well, I'm here to tell you that online poker bots are 100% real, and I know this because I've built one. And if I can build one, well. Anybody can build one. What's more, over the course of this multi-part article, I'll show you how.
c++  bot  hack  poker  online  software  windows  geek  how-to  api  algorithm  tip  programming 
may 2010 by rtopitt
The Matrix, but with money: the world of high-speed trading
Supercomputers pitted against one another in a high-stakes battle of attack and counterattack over a global network where predatory algorithms trawl the information stream, competing every millisecond to gain an informational advantage over rivals. It sounds like Hollywood fiction, but it's just an average trading day on the stock market.
economia  finança  artigo  tecnologia  nyse  nasdaq  eua  algorithm 
december 2009 by rtopitt
Technology Review: Trading Shares in Milliseconds
Today's stock market has become a world of automated transactions executed at lightning speed. This high-frequency trading could make the financial system more efficient, but it could also turn small mistakes into catastrophes.
economia  artigo  finança  trading  bolsa  eua  nyse  nasdaq  action  algorithm 
december 2009 by rtopitt
Software Craftsmanship – Katas
The Katacasts series consists of performance katas, done as screencasts, by Enrique Comba and me. Special guest appearances are planned by others. The screencasts are released weekly, usually between Tuesday and Thursday. A primary goal of the series is to provide inspiration for others to gain benefit from using katas in their own practice.
ruby  screencast  kata  how-to  geek  código-fonte  algorithm  tip  video  programming 
december 2009 by rtopitt
AI4R :: Artificial Intelligence for Ruby
AI4R is a collection of ruby algorithms implementations, covering several Artificial intelligence fields, and simple practical examples using them. A Ruby playground for AI researchers. It implements: Genetic algorithms, Self-organized maps (SOM), Neural Networks, Automatic classifiers (Machine Learning), Data clustering
ruby  gem  ia  rede_neural  clustering  machine_learning  importante  biblioteca  algorithm  programming 
november 2009 by rtopitt
Implementing the Pearson correlation algorithm using Ruby and the GNU Scientific Library
At its heart, acts_as_recommendable uses a statistical measure known as the Pearson correlation coefficient to calculate the “nearness” of items to one another. Alex talked about the performance issues he encountered when implementing the algorithm in pure ruby. To allow recommendations to be calculated for the entire database he had to switch to making calculations offline and reimplementing the algorithm in C using RubyInline .
ruby  rails  plugin  performance  c  gnu  estatística  algorithm  programming  recomendation 
november 2009 by rtopitt
the world according to matpalm
blog cheio de problemas estatísticos / computacionais divertidos
blog  nerd  geek  estatística  how-to  algorithm  analysis  programming 
november 2009 by rtopitt
Digital Face Beautification
This sketch presents a novel method for digital face beautification: given a frontal photograph of a face (a portrait), our method automatically increases the predicted attractiveness rating of the face. The main challenge is to achieve this goal while in
beleza  bizarrice  demonstração  edição  geek  algorithm  photography 
may 2009 by rtopitt
Liquid Rescale GIMP plugin: content-aware resizing for the GIMP
This site is about a GIMP plugin called Liquid Rescale. It is a free, open source frontend to the Liquid Rescale Library, which provides an implementation of the Seam Carving algorithm as described in this paper by Shai Avidan and Ariel Shamir.
edição  gimp  plugin  resize  seam_carving  algorithm  photography 
may 2009 by rtopitt
Enfuse - Wiki
Enfuse is a command-line program used to merge different exposures of the same scene to produce an image that looks very much like a tonemapped image (without the halos) but requires no creation of an HDR image. Therefore it is much simpler to use and all
edição  enfuse  exposição  hdr  linux  shell  algorithm  photography 
may 2009 by rtopitt
oldmoe: Document Matching In Ruby
Comparando elementos (objetos) em Ruby via Term-Frequency vector
objeto  ruby  algorithm  tip  programming 
may 2009 by rtopitt
SEOmoz | Reddit, Stumbleupon, and Hacker News Algorithms Exposed!
This week I continue by exposing how popular social media websites use algorithms to utilize user data.
social  web2.0  webapp  algorithm 
may 2009 by rtopitt
Sorting Algorithms Demo
The following applets chart the progress of several common sorting algorithms while sorting an array of data using in-place algorithms. This means that the algorithms do not allocate additional storage to hold temporary results: they sort the data in plac
applet  eficiência  geek  java  ordenação  algorithm  video  programming 
may 2009 by rtopitt
Slashdot | Time Running Out for Public Key Encryption
Two research teams have independently made quantum computers that run the prime-number-factorising Shor's algorithm — a significant step towards breaking public key cryptography.
chave_pública  computação_quântica  criptografia  física  geek  algorithm  security 
may 2009 by rtopitt
Michael's Knowledge Base
This is a categorical list of computer-related documentation I've written over the years.
artigo  computação  geek  algorithm  programming 
may 2009 by rtopitt
YouTube - Content Aware Image Resizing
Redimensionamento de imagens de maneira inteligente, incrível
artigo  edição  geek  imagem  redimensionamento  youtube  algorithm  video  photo 
may 2009 by rtopitt
Data Structures and Algorithms with Object-Oriented Design Patterns in Ruby
Livro sobre estruturas de dados e algoritmos, em padrões de projeto orientados à objetos, em Ruby, gratuito
estrutura_de_dados  grátis  livro  orientação_a_objetos  ruby  algorithm  programming 
may 2009 by rtopitt
The Sorting Algorithm Demo
Demonstração visual e com código de algoritmos de ordenação variados
java  algorithm  programming 
may 2009 by rtopitt

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