sorting

A visualization and sonification of 15 sorting algorithms, from selection sort to bogo sort, run on shuffled integers in six minutes. Each algorithm gets a size and speed scaled to its complexity.

Andrei Alexandrescu's CppCon 2019 talk revisits sorting, showing how branchless tricks, hybrid strategies and a cost metric can speed up std::sort-style algorithms on modern hardware.

A short tour of a UK materials recycling facility showing how mixed recyclables are mechanically and optically sorted. Aluminum, ferrous metal, glass, paper, and trash come out as separate streams.

A three-minute capture of SORTDEMO.BAS, the sorting visualization that shipped with QBasic. It animates insertion, bubble, heap, exchange, shell and quick sort with chiptune-like sound.

Hungarian folk dancers from Sapientia University act out the quicksort algorithm step by step, with music. It is part of the AlgoRythmics series of sorting algorithms performed as dance.

Dave Ackley demonstrates the Demon Horde Sort, an inherently robust sorting machine running in his Movable Feast Machine simulator. This is the uncut version with all details and side thoughts.

A one-minute clip from Barack Obama's 2008 Google visit in which Eric Schmidt asks him the most efficient way to sort a million 32-bit integers. Obama answers that bubble sort would be the wrong choice.

Dave Ackley gives a high-level introduction to robust-first computing, which prioritizes robustness over efficiency in computer architecture. A sorting demo illustrates the idea.

Matt Kulukundis explains how Google designed SwissTable, a fast, cache-friendly hash table, step by step from std::unordered_map. The talk covers open addressing, SIMD probing and the tradeoffs of changing a fundamental data structure.

Python core developer Raymond Hettinger explains how Python's dictionary implementation evolved into the compact, ordered dict in Python 3.6. He uses pictures and small bits of pure Python, and covers key-sharing, compaction and versioning.

Reducible's visual walkthrough of the Fast Fourier Transform, motivated by polynomial multiplication. It shows how the FFT's key ideas can be discovered by asking the right questions.

Chandler Carruth's CppCon 2014 talk on writing fast C++, explaining why data structure choice and memory layout matter more than clever algorithms. It covers why standard containers like unordered_map perform poorly on modern CPUs.

Juan Pedro Bolivar Puente explains immutable and persistent data structures in C++ and how they support value semantics. He presents the Immer library, rrb-trees, and a prototype text editor that opens a huge file instantly.

CGP Grey compares airplane boarding methods, based on an arXiv paper, and shows why the intuitive back-to-front approach is slow while random or outside-in boarding does better.

Tom Scott-style absurdist tour by Tom7 of SIGBOVIK chess projects: a tournament of 30 weird chess algorithms used to rate a color- and piece-blind chess program. Topics include mirrors, arithmetic encoding, perverted game tree search and a diluted Stockfish.

Donald Knuth's 2017 Christmas Tree Lecture at Stanford about a combinatorial geometry problem whose computed numbers matched a striking formula. He tells the story of the conjecture and its sequel.

A 2007 Google Tech Talk in which Cliff Click of Azul Systems presents a lock-free concurrent hash table that scales to 768 CPUs. He explains why it is correct by reasoning in a different way than usual happens-before and memory-order arguments.

A Dyalog demonstration of developing a Sudoku solver in APL, using an algorithm by Arthur Whitney with performance work by John Scholes. The narration steps through the array-oriented solution.

A feature-length Defunctland documentary on the history of Disney's FastPass and FastPass+ expedited queue systems. It covers how the systems evolved and how they were designed, with simulation of their effects on park lines.

Lee Byron of Facebook explains how persistent immutable data structures work and how to use them in React apps with Immutable.js. He covers memoization benefits and avoiding coupling through shared mutable state.

James Long's dotJS 2019 talk on how CRDTs enable local-first apps and how simple they can be to implement. He shows how to use them to build robust offline-capable frontends.

Guy Steele presents a small geometric problem and compares four computational approaches: a classic sequential solution and three parallel-friendly ones. Each is illustrated pictorially and with working code, weighing total work against time to solution.

Martin Kleppmann's QCon London 2018 talk on keeping data consistent in distributed systems without a central leader. It surveys CRDT algorithms for syncing devices and collaborative editing over peer-to-peer networks.

John Scholes builds a depth-first tree-search operator step by step in a Dyalog APL session. It covers higher-order functions and runs the search on the N-Queens problem.

A JSConf 2014 talk visually breaking down algorithms behind everyday UI patterns, such as dropdown menus that vanish when the mouse drifts and picking the nearest target to the cursor. It shows how these are implemented in JavaScript.

Erik Demaine's MIT 6.006 lecture introducing dynamic programming through Fibonacci numbers and shortest paths. It covers memoization, subproblems and optimal substructure.

Two Google engineers perform a mock coding interview and then discuss best practices for candidates, including asking clarifying questions and communicating while solving.

Anders Brownworth gives a basic visual introduction to blockchain using an interactive web demo, covering SHA256 hashes, blocks, chains, distribution, tokens and coinbase transactions.

Veritasium tells the story of the Fast Fourier Transform, from its use in detecting nuclear tests to Cold War politics, and how it could have changed the arms race. It includes a short, intuitive explanation of what the Fourier transform does.

Sean Parent's CppCon 2015 talk on better use of standard containers and the goal of having no incidental data structures. It argues that proper containers can greatly simplify code.

Redis Labs and Tim Davis present RedisGraph, which uses GraphBLAS to treat graph queries in Cypher as sparse linear algebra for lower latency.

Martin Donald explains the Wave Function Collapse algorithm using Sudoku-like constraint solving and shows how he implemented it with Blender and Godot. It links demos and reference articles.

Stephan T. Lavavej's CppCon 2019 talk on implementing floating-point to_chars and from_chars in Microsoft's C++ STL. It covers the history of float-string conversion and the algorithms that make it much faster.

Polylog explains how algorithms can be turned into circuits and encoded as satisfiability problems, which lets you effectively run them backwards. It uses this to motivate breaking RSA, general reductions to SAT, and what P vs NP is really asking.

Elasticsearch engineer and Lucene committer Adrien Grand explains the design decisions inside a Lucene index and what problems it can and cannot solve. The talk goes into how Lucene stores data for fast search and analytics.

A walkthrough of the Quake III fast inverse square root, explaining where the constant 0x5f3759df comes from. It covers IEEE 754 floats, the bit hack that approximates a logarithm, and a Newton's method refinement.

Martin Kleppmann surveys current research on CRDTs, the algorithms for merging concurrent edits across offline replicas. He covers the hard parts such as rich text, moves and merge results that are technically correct but poor.

Erik Demaine's MIT 6.851 Advanced Data Structures lecture introducing succinct data structures, covering rank, select and tries. It is part of the Spring 2012 course.

A bot built by Robin Baumgarten plays Infinite Mario using A* path-finding, shown as a red planned path that updates as new obstacles appear. It won the Mario AI competitions and uses only on-screen information.

Bryan Cantrill presents the ARC (Adaptive Replacement Cache) paper by Megiddo and Modha at Papers We Love. He opens with a survey of caching strategies before digging into the self-tuning LRU/MFU design.