Rabin-Karp: substring search and multi-pattern matching with a rolling hash.

Rabin-Karp slides a fixed-width hash over the text so each window costs O(1) to update, making it ideal for matching many patterns at once. The signal is the polynomial rolling hash, modular arithmetic, and why you still verify on a hash hit. Here is the answer.

Updated Aug 2026 · Grounded in real Applied AI Engineer interview loops and written to a senior-engineer editorial bar.