Breaking a Time-and-Space Barrier in Constructing Full-Text Indices

  • Authors:
  • Wing-Kai Hon;Kunihiko Sadakane;Wing-Kin Sung

  • Affiliations:
  • wkhon@cs.nthu.edu.tw;sada@csce.kyushu-u.ac.jp;ksung@comp.nus.edu.sg

  • Venue:
  • SIAM Journal on Computing
  • Year:
  • 2009

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Abstract

Suffix trees and suffix arrays are the most prominent full-text indices, and their construction algorithms are well studied. In the literature, the fastest algorithm runs in $O(n)$ time, while it requires $O(n\log n)$-bit working space, where $n$ denotes the length of the text. On the other hand, the most space-efficient algorithm requires $O(n)$-bit working space while it runs in $O(n\log n)$ time. It was open whether these indices can be constructed in both $o(n\log n)$ time and $o(n\log n)$-bit working space. This paper breaks the above time-and-space barrier under the unit-cost word RAM. We give an algorithm for constructing the suffix array, which takes $O(n)$ time and $O(n)$-bit working space, for texts with constant-size alphabets. Note that both the time and the space bounds are optimal. For constructing the suffix tree, our algorithm requires $O(n\log^{\epsilon}n)$ time and $O(n)$-bit working space for any $0