Efficient Implementation of the WARM-UP Algorithm for the Construction of Length-Restricted Prefix Codes (1999)
| Venue: | in Proceedings of the ALENEX |
| Citations: | 5 - 0 self |
BibTeX
@INPROCEEDINGS{Milidiu99efficientimplementation,
author = {Ruy Luiz Milidiu and Artur Alves Pessoa and Eduardo Sany Laber},
title = {Efficient Implementation of the WARM-UP Algorithm for the Construction of Length-Restricted Prefix Codes},
booktitle = {in Proceedings of the ALENEX},
year = {1999},
pages = {1--17},
publisher = {Springer-Verlag}
}
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Abstract
. Given an alphabet \Sigma = fa1 ; : : : ; ang with a corresponding list of positive weights fw1 ; : : : ; wng and a length restriction L, the length-restricted prefix code problem is to find, a prefix code that minimizes P n i=1 w i l i , where l i , the length of the codeword assigned to a i , cannot be greater than L, for i = 1; : : : ; n. In this paper, we present an efficient implementation of the WARM-UP algorithm, an approximative method for this problem. The worst-case time complexity of WARM-UP is O(n log n +n log wn ), where wn is the greatest weight. However, some experiments with a previous implementation of WARM-UP show that it runs in linear time for several practical cases, if the input weights are already sorted. In addition, it often produces optimal codes. The proposed implementation combines two new enhancements to reduce the space usage of WARM-UP and to improve its execution time. As a result, it is about ten times faster than the previous implementat...
