start your coding journey with our expert-designed, job-focused practical coding courses. learn to code from scratch with interactive, beginner-friendly lessons.

atcoder is a programming contest site for anyone from beginners to experts. we hold weekly programming contests online.

spoj (sphere online judge) is an online judge system with over 315,000 registered users and over 20000 problems. the solution to problems can be submitted in over 60 languages including c, c++, java, python, c#, go, haskell, ocaml, and f#. spoj has a rapidly growing problem set/tasks available for practice 24 hours/day, including many original tasks prepared by the community of expert problem setters associated with the project.

the goal of this project is to translate the wonderful resource http://e-maxx.ru/algo which provides descriptions of many algorithms and data structures especially popular in field of competitive programming. moreover we want to improve the collected knowledge by extending the articles and adding new articles to the collection.

a computer science portal for geeks. it contains well written, well thought and well explained computer science and programming articles, quizzes and practice/competitive programming/company interview questions.

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hackerrank is the market-leading technical assessment and remote interview solution for hiring developers. learn how to hire technical talent from anywhere!

stack overflow is the largest, most trusted online community for developers to learn, share​ ​their programming ​knowledge, and build their careers.

github is where over 100 million developers shape the future of software, together. contribute to the open source community, manage your git repositories, review code like a pro, track bugs and features, power your ci/cd and devops workflows, and secure code before you commit it.

learn to code in python, c/c++, java, and other popular programming languages with our easy to follow tutorials, examples, online compiler and references.