,
Zijin Huang
,
André van Renssen
,
Sampson Wong
Creative Commons Attribution 4.0 International license
We consider the problem of computing an approximate weighted shortest path in a weighted planar subdivision, with weights assigned from the set {0, 1, ∞}. The subdivision includes zero-cost regions (0-regions) with weight 0 and obstacles with weight ∞, all embedded in a plane with weight 1. In a polygonal domain, where the 0-regions and obstacles are non-overlapping polygons (not necessarily convex) with in total N vertices, we present an algorithm that computes a (1 + ε)-approximate spanner of the input vertices in expected Õ(N/ε³) time, for 0 < ε < 1. Using our spanner, we can compute a (1 + ε)-approximate weighted shortest path between any two points (not necessarily vertices) in Õ(N/ε³) time. Furthermore, we prove that our results more generally apply to non-polygonal convex regions. Using this generalisation, one can approximate the weak partial Fréchet similarity [Buchin et al., 2009] between two polygonal curves in expected Õ(n²/ε²) time, where n is the total number of vertices of the input curves.
@InProceedings{gudmundsson_et_al:LIPIcs.WADS.2025.33,
author = {Gudmundsson, Joachim and Huang, Zijin and van Renssen, Andr\'{e} and Wong, Sampson},
title = {{Spanner for the 0/1/∞ Weighted Region Problem}},
booktitle = {19th International Symposium on Algorithms and Data Structures (WADS 2025)},
pages = {33:1--33:15},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-398-0},
ISSN = {1868-8969},
year = {2025},
volume = {349},
editor = {Morin, Pat and Oh, Eunjin},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.WADS.2025.33},
URN = {urn:nbn:de:0030-drops-242644},
doi = {10.4230/LIPIcs.WADS.2025.33},
annote = {Keywords: weighted region problem, approximate shortest path, spanner}
}