사전코딩. 참고 : http://altools.tistory.com/60

makedic.pl

#!/usr/bin/env perl 

use strict;
use warnings;
use utf8;
use 5.010;
use YAML;

=pod

   w = NIL;
   add all possible charcodes to the dictionary
   for (every character c in the uncompressed data) do
       if ((w + c) exists in the dictionary) then
           w = w + c;
       else 
           add (w + c) to the dictionary;
           add the dictionary code for w to output;
           w = c;
       endif
   done
   add the dictionary code for w to output;
   display output;

=cut

sub makeDic{
    my @out;
    my @data = @_;
    my %map;

    map{ $map{$_}=0 }@data;

    my $w = '';
    foreach my $c (@data){
        if( defined($map{$w.$c}) ){
            $w = $w.$c;
        }
        else{
            $map{$w.$c}=0;
            push(@out,$w);
            $w = $c;
        }
    }
    push(@out,$w);
    return @out;
}
my @data = qw( D A B C E A B C E A B C E D );
my @out = makeDic(@data);
say "@data";
say "@out";

output:
D A B C E A B C E A B C E D
D A B C E AB CE ABC E D