Implements a lazy-propagation segment tree supporting range updates and range queries. The code is self-contained, uses only the standard library, and demonstrates a non-obvious implementation of a complex data structure that is reusable in many problems requiring interval operations.

Implements a Fenwick Tree (Binary Indexed Tree) for point updates and prefix sum queries, with support for range updates and point queries via two trees. The code is concise, efficient, and lacks any internal dependencies, making it trivial to extract.

Implements a Suffix Automaton for linear-time construction and various string processing tasks (e.g., substring occurrence, longest common substring). The implementation is self-contained and showcases advanced string algorithm knowledge.

Implements the Aho-Corasick automaton for multi-pattern string matching. Includes failure links and output links, enabling efficient dictionary matching. The code is self-contained and represents a non-trivial algorithm.

Provides a test harness for competitive programming solutions, including functions to assert expected output against given input samples and to run solutions with file-based test cases. This pattern is reusable across any problem that follows the standard I/O format and demonstrates skilled test automation.