Hands-on coding exercises, challenges, and real-world practice platforms.
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Free Resources (33)
- A2OJ Free
- Problem sets organized by difficulty and topic.
- Algo Deck Free
- Open-source collection of 200+ algorithmic flashcards for quick review and interview prep.
- Algomation Free
- Algorithm visualization library using JavaScript generators to animate execution of common algorithms.
- Algorithms Illuminated Free
- Tim Roughgarden's companion site with lecture videos and slides for his algorithms book series.
- AtCoder Problems Free
- AtCoder practice problems with difficulty ratings.
- basecs Free
- Medium blog by Vaidehi Joshi with illustrated in-depth tutorials on algorithms and data structures.
- Code Abbey Free
- Programming problems for beginners to experts.
- Codeforces - Problems Free
- Database of competitive programming problems.
- Codeground Free
- Practice platform with algorithmic problems.
- Competitive Programmer's Handbook Free
- Antti Laaksonen's free book introducing competitive programming for IOI and ICPC aspirants.
- CP-Algorithms Free
- Comprehensive archive of algorithms and data structures with implementations.
- CSES Problem Set Free
- Competitive Programming Essential Skills problem set.
- E-Maxx Algorithms Free
- Widely-referenced Russian tutorial site covering a huge range of competitive programming algorithms.
- GeeksforGeeks Free
- Computer science tutorials, algorithm explanations, and practice problems.
- HackerEarth Code Monk Free
- Step-by-step tutorials on essential competitive programming topics with practice problems.
- IDeserve YouTube Free
- YouTube channel with detailed algorithm and data structure interview tutorials and walkthroughs.
- Kattis Free
- Programming contest problems from various competitions.
- KTH KACTL Notebook Free
- Well-organized competitive programming team notebook from KTH Royal Institute.
- MIT 6.006 Introduction to Algorithms Free
- MIT OCW video lectures and materials for the classic undergraduate algorithms course.
- mycodeschool YouTube Free
- High-quality video tutorials on basic programming data structures and algorithms.
- NeetCode Free
- Curated coding problems for interview preparation.
- OI Wiki Free
- Community-driven Chinese wiki covering competitive programming algorithms and data structures.
- Project Euler Free
- Mathematical and computational programming problems.
- See Algorithms Free
- Interactive site that visualizes algorithms and lets users create and share custom graphs and trees.
- SPOJ Free
- Online judge with thousands of programming problems.
- Stanford CS 97SI Free
- Stanford's introduction to competitive programming with comprehensive lecture slides and practice problems.
- Topcoder Data Science Tutorials Free
- Classic tutorials by Topcoder members covering algorithms and data structures used in competition.
- USA Computing Olympiad Free
- USACO training pages with self-paced algorithmic problems to develop contest programming skills.
- USACO Guide Free
- Curated learning path for competitive programming from bronze to platinum.
- USFCA Algorithm Visualizations Free
- David Galles' interactive visualizations for sorting, graphs, trees, heaps and data structures.
- UVa Online Judge Free
- Classic programming problems and contests.
- VisualAlgo Free
- Interactive algorithm visualizations for sorting, graph, and data structure algorithms.
- William Fiset YouTube Free
- Comprehensive YouTube channel covering almost all data structures and algorithms with animations.