Covering Many or Few Points with Unit Disks

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

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

  • Venue:
  • Theory of Computing Systems
  • Year:
  • 2009

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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 algorithms that compute, for any fixed ε0, a (1−ε)-approximation to the optimal solution in O(nlog n) 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 computes, for any fixed ε0, in O(nlog 2 n) expected time a disk that is, with high probability, a (1+ε)-approximation to the optimal solution.