Password Hashing Competition
and our recommendation for hashing passwords: Argon2 Password hashing is everywhere, from web services' credentials storage to mobile and desktop authentication or disk encryption systems. Yet there wasn't an established standard to fulfill the needs of modern applications and to best protect against attackers. We started the Password Hashing Competition (PHC) to solve this problem. PHC ran from 2
How LZ4 works ·
Warning: This is the blog I wrote as a kid. Most of what is written here is probably wrong. Tue, Oct 25, 2016 LZ4 is a really fast compression algorithm with a reasonable compression ratio, but unfortunately there is limited documentation on how it works. The only explanation (not spec, explanation) can be found on the author's blog, but I think it is less of an explanation and more of an informal
Squash Compression Benchmark
The Squash library is an abstraction layer for compression algorithms, making it trivial to switch between them… or write a benchmark which tries them all, which is what you see here! The Squash Compression Benchmark currently consists of {{datasets.length|number}} datasets, each of which is tested against {{plugins.length}} plugins containing {{codecs.length|number}} codecs at every compression l
Page replacement algorithm - Wikipedia
This article is about algorithms specific to paging. For an outline of general cache algorithms (e.g. processor, disk, database, web), see Cache algorithms. In a computer operating system that uses paging for virtual memory management, page replacement algorithms decide which memory pages to page out, sometimes called swap out, or write to disk, when a page of memory needs to be allocated. Page re
Datastructures for external memory
Something I recently became interested in is map data structures for external memory — i.e. ways of storing indexed data that are optimized for storage on disk. In a typical analysis of algorithm time complexity, you assume it takes constant time to access memory or perform a basic CPU operation such as addition. This is of course not wholly accurate: in particular, cache effects mean that memory
Little's law - Wikipedia
In mathematical queueing theory, Little's law (also result, theorem, lemma, or formula[1][2]) is a theorem by John Little which states that the long-term average number L of customers in a stationary system is equal to the long-term average effective arrival rate λ multiplied by the average time W that a customer spends in the system. Expressed algebraically the law is The relationship is not infl
Simhashing (hopefully) made simple
Why Simhash? When it comes to figuring out how similar various pieces of data are from one another (and which is the closest matching one in a large group of candidates), simhashing is one of my favourite algorithms. It's somewhat simple, brilliant in its approach, but still not obvious enough for most people (myself included) to come up with it on their own. Readers may be familiar with hashing a
Wavelet TreeのTop-Kの改善 - 気ままなブログ
Wavelet Treeは強力なデータ構造ですが、ひとつどうしても気になる点があります。それは、Top-Kの列挙です。文字列本で紹介されているGreedyな方法は、結果がK件しか必要ないにもかかわらず、計算時間がけっこうかかります。他の操作は、最悪値の計算量が小さく、安心して使えるのに対して、Top-Kだけは、少し注意する必要があります。そのことは、文字列本にも書いてあって、最悪計算量も明示してあります。 その最悪計算量ですが、要素間の頻度に大きな偏りがある場合は、無断な節点を調べずに済み、計算量はO(klogσ)に近づくとあります。つまり、ある区間内の数値に偏りがあると、問題ないということです。 1 2 3 4 2 3 4 3 4 4上記のような場合だと、Top-1のクエリを発行すると、O(logσ)です。頻度に偏りがあると、Wavelet Treeの上段での見積もりがうまく機能するので
Bit Twiddling Hacks
By Sean Eron Anderson seander@cs.stanford.edu Individually, the code snippets here are in the public domain (unless otherwise noted) — feel free to use them however you please. The aggregate collection and descriptions are © 1997-2005 Sean Eron Anderson. The code and descriptions are distributed in the hope that they will be useful, but WITHOUT ANY WARRANTY and without even the implied warranty of
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GitHub - lithammer/go-jump-consistent-hash: :zap: Fast, minimal memory, consistent hash algorithm
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Cache replacement policies - Wikipedia
Algorithms | Computer science theory | Computing | Khan Academy
http://kellabyte.com/2014/09/23/batching-and-pipelining-linearizable-operations-in-replicated-logs/
VisuAlgo moves to https://visualgo.net/en
Algorithmic Gymnastics: We Need To Talk About Binary Search.
http://arxiv.org/pdf/1005.0662.pdf
Publications - superlinearindexes
CPM 2013: "1973+40=2013" (Special Session celebrating the 40th Anniversary of the Suffix Tree)
http://sharebookfree.com/category/algorithms/