An Optimal O(log log n)-Time Parallel Algorithm for Detecting all Squares in a String

  • Authors:
  • Alberto Apostolico;Dany Breslauer

  • Affiliations:
  • -;-

  • Venue:
  • SIAM Journal on Computing
  • Year:
  • 1996

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Abstract

An optimal $O(\log\log n)$-time concurrent-read concurrent-write parallel algorithm for detecting all squares in a string is presented. A tight lower bound shows that over general alphabets, this is the fastest possible optimal algorithm. When $p$ processors are available, the bounds become $\Theta(\lceil{({n\log n})/ p}\rceil + \log\log_{\lceil 1+p/n \rceil} 2p)$. The algorithm uses an optimal parallel string-matching algorithm together with periodicity properties to locate the squares within the input string.