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We are given a read-only memory for input and a write-only stream for output. For a positive integer parameter s, an s-workspace algorithm is an algorithm using only O(s) words of workspace in addition to the memory for input. In this paper, we present an O(n^2/s)-time s-workspace algorithm for subdividing a simple polygon into O(\min\{n/s,s\}) subpolygons of complexity O(\max\{n/s,s\}).
As applications of the subdivision, the previously best known time-space trade-offs for the following three geometric problems are improved immediately: (1) computing the shortest path between two points inside a simple n-gon, (2) computing the shortest path tree from a point inside a simple n-gon, (3) computing a triangulation of a simple n-gon. In addition, we improve the algorithm for the second problem even further.
@InProceedings{oh_et_al:LIPIcs.ISAAC.2017.61,
author = {Oh, Eunjin and Ahn, Hee-Kap},
title = {{A New Balanced Subdivision of a Simple Polygon for Time-Space Trade-off Algorithms}},
booktitle = {28th International Symposium on Algorithms and Computation (ISAAC 2017)},
pages = {61:1--61:12},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-054-5},
ISSN = {1868-8969},
year = {2017},
volume = {92},
editor = {Okamoto, Yoshio and Tokuyama, Takeshi},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ISAAC.2017.61},
URN = {urn:nbn:de:0030-drops-82401},
doi = {10.4230/LIPIcs.ISAAC.2017.61},
annote = {Keywords: Time-space trade-off, simple polygon, shortest path, shortest path tree}
}