use strict;  
use warnings;   
  
@ARGV =  ('a,b|c', 'c,d|e', 'a,d|e') unless @ARGV;   
  
my %HoA;  
foreach ( @ARGV ) {  
    m/^([a-z])[,]([a-z])[|]([a-z])$/ ;  
    push @{$HoA{$1}}, $2;  
}  
print "\n===========\@HoA=====\n";  
print "from->to\n";  
while (my ($key, $values) = each %HoA) {  
    print $key, "=>   [", join(',', @$values), "]\n";  
}   
 
-----------OUTPUT---------- 
[hzing@localhost perl]$ perl input.pl  
 
===========@HoA===== 
from->to 
c=>   [d] 
a=>   [b,d]