Online and Offline Algorithms for Counting Distinct Closed Factors via Sliding Suffix Trees

Fuente: arXiv
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Auteurs principaux: Mieno, Takuya, Takahashi, Shun, Seto, Kazuhisa, Horiyama, Takashi
Format: Preprint
Publié: 2024
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author Mieno, Takuya
Takahashi, Shun
Seto, Kazuhisa
Horiyama, Takashi
author_facet Mieno, Takuya
Takahashi, Shun
Seto, Kazuhisa
Horiyama, Takashi
contents A string is said to be closed if its length is one, or if it has a non-empty factor that occurs both as a prefix and as a suffix of the string, but does not occur elsewhere. The notion of closed words was introduced by [Fici, WORDS 2011]. Recently, the maximum number of distinct closed factors occurring in a string was investigated by [Parshina and Puzynina, Theor. Comput. Sci. 2024], and an asymptotic tight bound was proved. In this paper, we propose two algorithms to count the distinct closed factors in a string T of length n over an alphabet of size σ. The first algorithm runs in O(n log σ) time using O(n) space for string T given in an online manner. The second algorithm runs in O(n) time using O(n) space for string T given in an offline manner. Both algorithms utilize suffix trees for sliding windows.
format Preprint
id arxiv_https___arxiv_org_abs_2409_19576
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Online and Offline Algorithms for Counting Distinct Closed Factors via Sliding Suffix Trees
Mieno, Takuya
Takahashi, Shun
Seto, Kazuhisa
Horiyama, Takashi
Data Structures and Algorithms
A string is said to be closed if its length is one, or if it has a non-empty factor that occurs both as a prefix and as a suffix of the string, but does not occur elsewhere. The notion of closed words was introduced by [Fici, WORDS 2011]. Recently, the maximum number of distinct closed factors occurring in a string was investigated by [Parshina and Puzynina, Theor. Comput. Sci. 2024], and an asymptotic tight bound was proved. In this paper, we propose two algorithms to count the distinct closed factors in a string T of length n over an alphabet of size σ. The first algorithm runs in O(n log σ) time using O(n) space for string T given in an online manner. The second algorithm runs in O(n) time using O(n) space for string T given in an offline manner. Both algorithms utilize suffix trees for sliding windows.
title Online and Offline Algorithms for Counting Distinct Closed Factors via Sliding Suffix Trees
topic Data Structures and Algorithms
url https://arxiv.org/abs/2409.19576