IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences
Online ISSN : 1745-1337
Print ISSN : 0916-8508
Special Section on Discrete Mathematics and Its Applications
Packed Compact Tries: A Fast and Efficient Data Structure for Online String Processing
Takuya TAKAGIShunsuke INENAGAKunihiko SADAKANEHiroki ARIMURA
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2017 Volume E100.A Issue 9 Pages 1785-1793

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Abstract

We present a new data structure called the packed compact trie (packed c-trie) which stores a set S of k strings of total length n in nlog σ+O(klog n) bits of space and supports fast pattern matching queries and updates, where σ is the alphabet size. Assume that α=logσn letters are packed in a single machine word on the standard word RAM model, and let f(k,n) denote the query and update times of the dynamic predecessor/successor data structure of our choice which stores k integers from universe [1,n] in O(klog n) bits of space. Then, given a string of length m, our packed c-tries support pattern matching queries and insert/delete operations in $O(\frac{m}{\alpha} f(k,n))$ worst-case time and in $O(\frac{m}{\alpha} + f(k,n))$ expected time. Our experiments show that our packed c-tries are faster than the standard compact tries (a.k.a. Patricia trees) on real data sets. We also discuss applications of our packed c-tries.

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© 2017 The Institute of Electronics, Information and Communication Engineers
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