Untangled Monotonic Chains and Adaptive Range Search

  • Authors:
  • Diego Arroyuelo;Francisco Claude;Reza Dorrigiv;Stephane Durocher;Meng He;Alejandro López-Ortiz;J. Ian Munro;Patrick K. Nicholson;Alejandro Salinger;Matthew Skala

  • Affiliations:
  • Yahoo! Research Latin America, Chile;Cheriton School of Computer Science, University of Waterloo, Waterloo, Canada;Cheriton School of Computer Science, University of Waterloo, Waterloo, Canada;Department of Computer Science, University of Manitoba, Winnipeg, Canada;Cheriton School of Computer Science, University of Waterloo, Waterloo, Canada;Cheriton School of Computer Science, University of Waterloo, Waterloo, Canada;Cheriton School of Computer Science, University of Waterloo, Waterloo, Canada;Cheriton School of Computer Science, University of Waterloo, Waterloo, Canada;Cheriton School of Computer Science, University of Waterloo, Waterloo, Canada;Cheriton School of Computer Science, University of Waterloo, Waterloo, Canada and Department of Computer Science, University of Toronto, Toronto, Canada

  • Venue:
  • ISAAC '09 Proceedings of the 20th International Symposium on Algorithms and Computation
  • Year:
  • 2009

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Abstract

We present the first adaptive data structure for two-dimensional orthogonal range search. Our data structure is adaptive in the sense that it gives improved search performance for data with more inherent sortedness. Given n points on the plane, the linear-space data structure can answer range queries in O(logn + k + m) time, where m is the number of points in the output and k is the minimum number of monotonic chains into which the point set can be decomposed, which is $O(\sqrt{n})$ in the worst case. Our result matches the worst-case performance of other optimal-time linear-space data structures, or surpasses them when $k=o(\sqrt{n})$. Our data structure can also be made implicit, requiring no extra space beyond that of the data points themselves, in which case the query time becomes O(k logn + m). We present a novel algorithm of independent interest to decompose a point set into a minimum number of untangled, same-direction monotonic chains in O(kn + nlogn) time.