Interviewing at Google is tough. Put your coding and math chops to the test with this fun and challenging question from a past interview. The Question Given a graph G, count the number of unique k-step paths from node X to node Y for every pair of nodes X and Y.

A conceptual guide — Gaussian processes (GPs) are a flexible class of nonparametric machine learning models commonly used for modeling spatial and time series data. A common application of GPs is regression. For example, given incomplete geographical weather data, such as temperature or humidity, how can one recover values at unobserved locations? If one…

JavaScript is probably one of the most influential programming languages of all time (whether for good or bad) — it runs in almost every modern web browser regardless of the operating system. Whether you are using Safari, Chrome, or Firefox on MacOS, Windows, or Linux, JavaScript will be running behind…

A Beginner’s Guide. — Table of Contents 1. Python 2. MATLAB 3. R 4. SQL 5. Bash 1. Python Many programmers’ first language is Python. It’s a high-level, general-purpose programming language with hundreds of thousands of open source packages. Python is used for game development, data analysis, machine learning, finance, and just about every application you…

6 Command Line Utilities to Improve Your Efficiency — For many new developers, using the terminal or command line might seem inefficient or even antiquated. However, the shell is one of the most useful tools available to any developer. In this article, I will show you six useful utilities to level up your terminal game! Table of Contents 1…

You’re already familiar with Git basics: pushing and pulling, staging and committing files, merging and rebasing. Here are some slightly more advanced (yet useful) features we believe every programmer should know. 1. Creating a Pull Request You can create a pull request to propose updates to a public repository. First, navigate to the GitHub page…

In a large-scale company that operates a service with hundreds of millions of clients or users, data is vital to constructing feedback loops and informing business strategy. A firm as large as Netflix or Google collects enormous amounts of data pertaining to everything from daily active users to advertisement conversion…

A Case Study using Bitcoin, Ethereum, Cardano, and more. — Introduction The Kelly criterion is a well-known strategy for sizing bets to maximize long-run expected log wealth. It is widely applied to sports betting and casino gambling. Most sources provide coverage only for the single-asset case, however. We discuss the Kelly criterion for balancing a portfolio with multiple assets — taking…

The definitive mathematical guide. — Ordinary least squares regression is a standard technique everyone should be familiar with. We motivate the linear model from the perspective of the Gauss-Markov Theorem, discern between the overdetermined and underdetermined cases, and apply OLS regression to a wine quality dataset. Contents The Linear Model The Gauss Markov Theorem The Underdetermined…