Covering many or few points with unit disks

  • Authors:
  • Mark de Berg;Sergio Cabello;Sariel Har-Peled

  • Affiliations:
  • Department of Computer Science, TU Eindhoven, The Netherlands;Department of Mathematics, FMF, University of Ljubljana, and Department of Mathematics, IMFM, Slovenia;Department of Computer Science, University of Illinois

  • Venue:
  • WAOA'06 Proceedings of the 4th international conference on Approximation and Online Algorithms
  • Year:
  • 2006

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Abstract

Let P be a set of n weighted points. We study approximation algorithms for the following two continuous facility-location problems. In the first problem we want to place m unit disks, for a given constant m≥1, such that the total weight of the points from P inside the union of the disks is maximized. We present a deterministic algorithm that can compute, for any ε0, a (1−ε)-approximation to the optimal solution in O(n logn + ε$^{{\rm -4}{\it m}}$log$^{\rm 2{\it m}}$ (1/ε)) time. In the second problem we want to place a single disk with center in a given constant-complexity region X such that the total weight of the points from P inside the disk is minimized. Here we present an algorithm that can compute, for any ε0, with high probability a (1+ε)-approximation to the optimal solution in O(n (log3n + ε−4 log2n )) expected time.