Beginning Java Data Structures and Algorithms

Rabin-Karp

In 1987, Richard M. Karp and Michael O. Rabin proposed a string matching algorithm that performs well in practice and generalizes string matching against a set of patterns. The Rabin-Karp algorithm takes O(m) time in its preprocessing stage and its worst-case running time is O((n - m + 1)m), similar to Boyer-Moore's.

To better introduce the Rabin-Karp algorithm, let's assume that our alphabet ∑ is composed only of decimal digits (∑ = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9}), so that we can view a string of k characters as a decimal number with length k. Therefore, string 12345 corresponds to number 12345. Given a pattern P[0...m] and a substring from text T[i...i + m], if we convert both those strings to their correspondent decimal number, ...