donnemartin/interactive-coding-challenges

Interactive Coding Challenges is a collection of over 120 Python coding problems focused on the algorithms and data structures that commonly appear in technical job interviews. What makes it different from a static problem list is that it uses Jupyter Notebooks, which are interactive documents that mix explanatory text with runnable code cells. Each problem has a challenge notebook where you implement a solution and a separate solution notebook you can reference if you get stuck. Every challenge follows a consistent structure: the problem statement, any constraints or assumptions, the test cases that your solution must pass (including edge cases), the algorithm approach (blank in the challenge notebook, filled in the solution notebook), space for your code, and automated unit tests that run directly in the notebook to verify your solution immediately. Time and space complexity analysis is also provided for each solution. The 120 challenges are organized into categories including arrays and strings, linked lists, stacks and queues, graphs and trees, sorting, recursion and dynamic programming, bit manipulation, and mathematics. The repository also includes standalone reference implementations of common data structures like linked lists, binary search trees, heaps, and hash maps that you can study independently. As a complement, the repository includes a downloadable Anki flashcard deck for spaced repetition review of key concepts. Anki is a flashcard app that schedules reviews based on how well you remember each card. You would use this when preparing for technical coding interviews, practicing algorithm problem solving interactively, or learning how classic algorithms are implemented in Python. The tech stack is Python running in Jupyter Notebooks. Solutions can be run locally after cloning the repository or in the browser via Binder without any installation.