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

Rabin-Karp slides a fixed-width hash across the text so each window costs O(1) to update, which makes 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 Sep 2026 · Grounded in real GenAI, LLM, and AI/ML engineering interview loops and written to a senior-engineer editorial bar.