We consider a simple decremental data structure for maintaining a set of integers, that supports initializing the set to {1,2,…,n} followed by d deletions and s successor queries in arbitrary order in total 𝒪(n+d+s⋅(1+log_{max(2,s/n)} min(s,n))) time. The data structure consists of a single array of n integers. A straightforward modification allows the data structure to also support p predecessor and r range queries, with a total output k, in total 𝒪(n+d+k+q ⋅ (1+log_{max(2,q/n)} min(q,n))) time, where q = s+p+r. The data structure is essentially a special case of the classic union-find data structure with path compression but with unweighted linking (i.e., without linking by rank or size), that is known to achieve logarithmic amortized time bounds (Tarjan and van Leeuwen, 1984). In this paper we study the efficiency of this simple data structure, and compare it to other, theoretically superior, data structures.
@InProceedings{brodal:LIPIcs.SEA.2025.8, author = {Brodal, Gerth St{\o}lting}, title = {{A Simple Integer Successor-Delete Data Structure}}, booktitle = {23rd International Symposium on Experimental Algorithms (SEA 2025)}, pages = {8:1--8:16}, series = {Leibniz International Proceedings in Informatics (LIPIcs)}, ISBN = {978-3-95977-375-1}, ISSN = {1868-8969}, year = {2025}, volume = {338}, editor = {Mutzel, Petra and Prezza, Nicola}, publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik}, address = {Dagstuhl, Germany}, URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2025.8}, URN = {urn:nbn:de:0030-drops-232461}, doi = {10.4230/LIPIcs.SEA.2025.8}, annote = {Keywords: Successor queries, deletions, interval union-find, union-find} }
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