Improved selection in totally monotone arrays

Yishay Mansour, James K. Park, Baruch Schieber, Sandeep Sen

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

This paper’s main result is an O((√m lg m)(n lg n)+m lg n)-time algorithm for computing the kth smallest entry in each row of an m × n totally monotone array. (A two-dimensional array A = {a[i,j]} is totally monotone if for all i1 < i2 and j1 < j2, a[i1,j1] < a[i1, j2] implies a[i2, j1] < a[i2, j2].) For large values of k (in particular, for k = n/2'|), this algorithm is significantly faster than the O(k(m + n))-time algorithm for the same problem due to Kravets and Park (1991). An immediate consequence of this result is an O(n3/2 lg2 n)-time algorithm for computing the kth nearest neighbor of each vertex of a convex n-gon. In addition to the main result, we also give an O(n lg m)-time algorithm for computing an approximate median in each row of an m × n totally monotone array; this approximate median is an entry whose rank in its row lies between [n/4] and [3n/4].

Original languageAmerican English
Title of host publicationFoundations of Software Technology and Theoretical Computer Science - 11th Conference, Proceedings
EditorsSomenath Biswas, Kesav V. Nori
PublisherSpringer Verlag
Pages347-359
Number of pages13
ISBN (Print)9783540549673
DOIs
StatePublished - 1991
Externally publishedYes
Event11th Conference on Foundations of Software Technology and Theoretical Computer Science, FST and TCS, 1991 - New Delhi, India
Duration: Dec 17 1991Dec 19 1991

Publication series

NameLecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
Volume560 LNCS

Conference

Conference11th Conference on Foundations of Software Technology and Theoretical Computer Science, FST and TCS, 1991
Country/TerritoryIndia
CityNew Delhi
Period12/17/9112/19/91

ASJC Scopus subject areas

  • Theoretical Computer Science
  • General Computer Science

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