Elementary Yet Precise Worst-Case Analysis of Floyd's Heap-Construction Program

  • Authors:
  • Marek A. Suchenek

  • Affiliations:
  • (Correspd.) (Gratitude to Victor W. Marek, Philip Wadler, Greg Morrisett, Damian Niwiński, Ken Leyba, an Anonymous Referee of POPL'12, and - last but not least - the Ed. Bd. and the Anonymous ...

  • Venue:
  • Fundamenta Informaticae
  • Year:
  • 2012

Quantified Score

Hi-index 0.00

Visualization

Abstract

The worst-case behavior of the heap-construction phase of Heapsort escaped mathematically precise characterization by a closed-form formula for almost five decades. This paper offers a proof that the exact number of comparisons of keys performed in the worst case during construction of a heap of size N is: 2N − 2s2(N) − e2(N), where s2(N) is the sum of all digits of the binary representation of N and e2(N) is the exponent of 2 in the prime factorization of N. It allows for derivation of this best-known upper bound on the number of comparisons of Heapsort: (2N − 1)[lgN] − 2[lgN]+1 − 2s2(N) − e2(N) + 5.