Parallel Binary Search

  • Authors:
  • S. G. Akl;H. Meijer

  • Affiliations:
  • -;-

  • Venue:
  • IEEE Transactions on Parallel and Distributed Systems
  • Year:
  • 1990

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Abstract

Two arrays of numbers sorted in nondecreasing order are given: an array A of size n and an array B of size m, where nm. It is required to determine, for every element of A, the smallest element of B (if one exists) that is larger than or equal to it. It is shown how to solve this problem on the EREW PRAM (exclusive-read exclusive-write parallel random-access machine) in O(logm logn/log log m) time using n processors. The solution is then extended to the case in which fewer than n processors are available. This yields an EREW PRAM algorithm for the problem whose cost is O(n log m, which is O(m)) for nor=m/log m. It is shown how the solution obtained leads to an improved parallel merging algorithm.