Time and space efficient search for small alphabets with suffix arrays

To search a pattern P in a text, index data structures such as suffix trees and suffix arrays are widely used. It is known that searching with suffix trees is faster than with suffix arrays in the aspect of time complexity. But recently, a few linear-time search algorithms for constant-size alphabet in suffix arrays have been suggested. One of such algorithms proposed by Sim et al. uses Burrows-Wheeler transform and takes O(vertical bar P vertical bar log vertical bar Sigma vertical bar) time. But this algorithm needs too much space compared to Abouelhoda et al.'s algorithm to search a pattern. In this paper we present an improved version for Sim et al.'s algorithm. It needs only 2n bytes at most if a given alphabet is sufficiently small.