Rosetta Code

Move-to-front algorithm: Difference between revisions

Page Discussion

Move-to-front algorithm (view source)

Revision as of 20:16, 12 July 2017

11 bytes added ,  6 years ago
m
→‎version 2: changed some comments and whitespace, used a template for output.
No edit summary
m (→‎version 2: changed some comments and whitespace, used a template for output.)
Line 1,743:
parse arg xxx; if xxx='' then xxx= 'broood bananaaa hiphophiphop' /*use the default?*/
one=1 /*(offset) for this task's requirement.*/
do j=1 for words(xxx); x=word(xxx, j) /*process a single word at a time. */
@= 'abcdefghijklmnopqrstuvwxyz'; @@=@ /*symbol table: the lowercase alphabet */
$= /*set the decode string to a null. */
do k=1 for length(x); z=substr(x, k, 1) /*encrypt a symbol in the word. */
_=pos(z, @); if _==0 then iterate /*the symbol position in symbol table. */
$=$ _ - one; @=z || delstr(@, _, 1) /*(re-)adjust the symbol table string. */
end /*k*/ /* [↑] the move─to─front encoding. */
!= /*set the encode string to a null. */
do m=1 for words($); n=word($, m) +one /*decode the sequence table string. */
y=substr(@@, n, 1); !=! || y /*the decode symbol for the word. N word. */
@@=y || delstr(@@, n, 1) /*rebuild the symbol table string. */
end /*m*/ /* [↑] the move─to─front decoding. */
 
say ' word: ' left(x, 20) "encoding:" left($, 35) word('wrong OK', 1+(!==x) )
end /*j*/ /*stick a fork in it, we're all done. */</lang>
'''{{out|output''' |text=&nbsp; when using the default input:}}
<pre>
word: broood encoding: 1 17 15 0 0 5 OK
Retrieved from "https://rosettacode.org/wiki/Special:MobileDiff/247146"