algorithms

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.

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.

Glenn Vanderburg presents Cló, a Clojure library that reimplements TeX's core typesetting algorithms as composable functions. He shows what translating procedural, literate-programming code into functional form teaches.

A Technology Connections video essay arguing that algorithmic feeds make people passive about finding content, leading to complacency in how they seek information. It urges people to actively choose what they consume.

Lukas Eder's Devoxx talk on how modern cost-based SQL optimizers rewrite and plan queries in ways developers would not expect. It argues that declarative SQL, used well, can run complex queries very fast.

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.

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

Jon Bentley walks through three implementations of Hoare's Quicksort, from a dozen-line C function to a series of systematic code transformations that make the program ever simpler and more powerful. It is a Google Tech Talk on code elegance and program derivation.

Matt Parker follows the community effort to speed up his slow Wordle-solving code, which ended up running hundreds of millions of times faster. He walks through the techniques contributors used.

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.

Tom Scott's Royal Institution discourse on science communication in the age of social media, how recommendation algorithms shape popularity, and why view counts can matter more than truth. It includes a segment on parasocial relationships.

Peter Shor tells the story of how he discovered Shor's Algorithm, from his early mathematics days to the quantum factoring breakthrough. It was recorded at MIT at the Physics of Computation conference.

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.

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 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.

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.

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

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.

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

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.

Neil Fraser of Google presents Differential Synchronization, the algorithm behind MobWrite, for keeping multiple copies of a document in sync in real time. The talk argues the approach is robust, convergent and efficient.

Aaron Hsu shows how to manipulate and transform tree data in APL using arrays and inverted tables instead of pointers. He claims much smaller code, better performance and easier parallelisation.

Daniel Lemire's QCon talk on how simdjson parses gigabytes of JSON per second. It covers SIMD vectorization, branch prediction and the lessons learned building a fast parser.

AlphaPhoenix uses Monte Carlo simulation and annealing-style methods to draw North Carolina congressional district maps, both gerrymandered and fair. He focuses on the fascinating computational problem rather than the politics.

Matt Kulukundis reviews two years of Abseil's Swiss table hashtable, covering post-release optimizations, lessons from rolling it out across Google, design choices, and what global monitoring revealed.

Tom Scott races a London black-cab driver who has memorized The Knowledge against a phone GPS across the city, comparing local expertise to navigation software.

3Blue1Brown uses Wordle as an excuse to teach information theory and entropy, building a solver that picks guesses by expected information and incorporating word frequencies.

Uber Engineering's Joseph Gilley explains why Uber uses hexagons for geospatial indexing and introduces H3, its open source hierarchical grid system. He covers use cases and how distortion is handled.

Chandler Carruth's CppCon 2016 talk on designing hybrid data structures for performance. He covers cache locality, working-set size and allocation overhead, and why standard C++ containers fall short.

Technosociologist Zeynep Tufekci argues that the machine-learning systems used to serve ads also decide what political and social information people see. She explains how opaque algorithms can nudge, segment and manipulate users, and warns that the real danger is powerful people using AI to control populations.

A Channel 4 News interview with technologist Jaron Lanier, who argues that social media damages people's lives. He discusses how Facebook, YouTube and Google use algorithms and data collection to shape what users see.

Andrew Ng presents unsupervised feature learning and deep learning, showing how algorithms can learn representations from unlabeled data instead of hand-designed features. He gives examples in vision and audio, including visualizations of features learned by successive layers.

Rich Hickey introduces transducers in Clojure, a way to make map, filter and similar algorithms composable independent of the data source. This avoids duplicated implementations and intermediate collections across sequences, channels and streams.

Julia co-creator Stefan Karpinski explains why multiple dispatch makes Julia code and types reusable across packages with so little friction. He covers sharing basic types and sharing generic algorithms.

David Sachs of InvenSense explains how gyroscopes, accelerometers and compasses work on their own and together, demonstrated on a modified Android handset. He covers sensor fusion algorithms and why rotation math such as Euler angles matters.

Martin Kleppmann's Strange Loop talk on database transactions, covering why they were dropped by NoSQL, their reputation for being slow, and newer algorithms that make serializable transactions perform and scale. It touches on consistency, linearizability and the CAP theorem.

Veritasium's Derek Muller explains his hypothesis that YouTube's algorithm, not viewer preference, drives views, and that click-through rate has become the key metric. He argues this pushes creators toward clickable titles and thumbnails and leads to burnout.

A Veritasium video on how a feud between Russian mathematicians led to Markov chains and the modern prediction algorithms built on them. It covers the history and the math behind them.

A Philosophy Tube video essay on data, surveillance and the algorithms built on personal information, touching on Cambridge Analytica and the 'nothing to hide' argument.