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Problems

Basics first, then the classics, then company-style assessments. Every problem has tests you run right here; multi-level ones unlock as you go. See the roadmap.

Advanced & competitive

String hashing

Rolling hashes and Rabin-Karp.

String hashing / Rabin-Karp quiz

Spot the pattern Quiz on all of it

6 problems

Advanced & competitive

String hashing Rolling hashes and Rabin-Karp.

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Longest repeated substring py · c++ · java hard
All periods of a string py · c++ · java medium
Find every pattern occurrence py · c++ · java easy