Length-restricted coding using modified probability distributions
ACSC '01 Proceedings of the 24th Australasian conference on Computer science
ALENEX '99 Selected papers from the International Workshop on Algorithm Engineering and Experimentation
Incremental Calculation of Minimum-Redundancy Length-Restricted Codes
DCC '02 Proceedings of the Data Compression Conference
Distribution-Sensitive construction of minimum-redundancy prefix codes
STACS'06 Proceedings of the 23rd Annual conference on Theoretical Aspects of Computer Science
| Hi-index | 754.84 |
We consider the problem of calculating minimum-redundancy codes for alphabets in which there is significant repetition of symbol weights. On a sorted-by-weight alphabet of, n symbols and r distinct symbol weights we show that a minimum-redundancy prefix code can be constructed in O(r+r log(n/r)) time, and that a minimum redundancy L-bit length-limited prefix code can be constructed in O(Lr+Lrlog(n/r)) time. When r is small relative to n-which is necessarily the case for most practical coding problems on large alphabets-these bounds represent a substantial improvement upon the best previous algorithms for these two problems, which consumed O(n) time and O(nL) time, respectively. The improved algorithms are also space-efficient