#!/usr/bin/perl
# usage: ./generate_ACGT_01.pl
use strict;
use warnings;
use Math::Combinatorics;
#
my @n = qw(A C G T);
my $o1 = Math::Combinatorics->
  new(count=>1, data=>[@n], frequency=>[1, 1, 1, 1]);
my $o2 = Math::Combinatorics->
  new(count=>2, data=>[@n], frequency=>[2, 2, 2, 2]);
my $o3 = Math::Combinatorics->
  new(count=>3, data=>[@n], frequency=>[3, 3, 3, 3]);
my $o4 = Math::Combinatorics->
  new(count=>4, data=>[@n], frequency=>[4, 4, 4, 4]);
my @b = ();
#
foreach my $o ($o1, $o2, $o3, $o4) {
    while(my @ox = $o->next_multiset) {
      my $p = Math::Combinatorics->
	new(data=>\@ox, frequency=>[map{1} @ox]);
      while(my @oy = $p->next_string) {
	push@b, join('', @oy);
      }
    }
}
#
foreach my $e (@b) {
  foreach my $f (@b) {
    print$e.','.$f."\n"
  }
}
# eof

##</code><code>##

#!/usr/bin/perl
# usage: | test_ACGT_01.pl
use strict;
use warnings;
## no valued added (petty) to Loops try 2 : Y
#my $side = qr/(?:([ACGT])(?![^,]*\g{-1})){1,4}/;
## try 1 from Loops : N
#my $side = qr/(?:([ACGT])(?![^,]*\1))+/;
## try 2 from Loops : Y
my $side = qr/(?:([ACGT])(?![^,]*\g{-1}))+/;
##
while (<>) {
  chomp;
  print "$_ ". (/^$side,$side$/ ? 'Y' : 'N') . $/;
}
# eof

##</code><code>##

$ ./generate_ACGT_01.pl > y
$ cat y | ./test_ACGT_01.pl > x
$ less x