CSES

Antti Laaksonen's Competitive Programmer's Handbook, a free guide to algorithms and techniques for programming contests, is circulating widely among developers. The roughly 300-page book, published via the CSES project in Finland, covers topics from data structures to dynamic programming and graph algorithms, and is commonly recommended preparation for contests like ICPC and Codeforces.

Antti Laaksonen's free book 'Competitive Programmer's Handbook', published in 2018 by the University of Helsinki's CSES project, is being shared as a direct PDF link in programming circles. The freely available guide covers algorithms and data structures used in competitive programming contests, and continues to be recommended to students and developers preparing for coding competitions and technical interviews.