The problems are divided into easy, medium, and hard. Inside each file I have noted the prerequesites for being able to answer the question easily, along with tags.

For now all the solutions I've given are in Python/pseudocode (my excuse if code doesn't actually run). Feel free to add solutions in other languages. Also, the way this is set up is ideal for mock interviewers (helpful tags, solutions and hints), let me know if there are any ways you can think of to make this more helpful to people practicing.

Please free to add notes to questions, improve solutions, and add more questions. Please don't add questions that you've heard in actual interviews unless you're sure that it is compliant with the company's policies. Thanks a lot, and hope this is useful.