Out of memory during ridiculously large request at 438502.pl line 17.

##</code><code>##

use strict;
use warnings;
use re 'eval';

my @denoms = (10, 6, 5, 1);
my $expr = join '', map "((?:$_)*)", map '1' x $_, @denoms;

print "E=$expr\n";

sub greedy_change {
    my $change = shift;
    my $coin_count = 0;
    my @combo;
    $_ = ('1' x $change);
print "Trying to change $change with @denoms...\n";
print "$expr on $_\n";
    if (
    m{^$expr$
      (?{&regex_sub( \$coin_count, \$change, \@combo )})
    }x) {
        print "Matched!\n";
    }
    if ($coin_count) {
        print "C=$coin_count\n";
    }
    else {
        print "No matching combination found\n";
    }
    @combo;
}

for my $num (12, 14, 36) {
    my @change = greedy_change($num);
    print "$num: @change\n";
}

sub regex_sub
{
    my ($coin_count,$change,$combo) = @_;
    print "Code doesn't get run after once.\n";
    my @lengths = ($+[1]);
    my $new_count = 0;
    $lengths[$_] = $+[$_+1] - $+[$_] for 1..$#denoms;
    $new_count += $lengths[$_]/$denoms[$_] for 0..$#denoms;
    if (!$$coin_count or $new_count < $$coin_count) {
        print "$$change: $new_count is better than $$coin_count\n";
        $$coin_count = $new_count;
        @$combo = @lengths;
    }
}

##</code><code>##

...
  DB<1> s
main::regex_sub(438502.pl:40):      print "Code doesn't get run after once.\n";
  DB<1> s
Code doesn't get run after once.
main::regex_sub(438502.pl:41):      my @lengths = ($+[1]);
  DB<1> p scalar @+
5
  DB<2> p join ":",@+
12:10:10:10:12
  DB<3> s
main::regex_sub(438502.pl:42):      my $new_count = 0;
  DB<3> p @lengths   
10
  DB<4> p join ":",@+
23:22:23

##</code><code>##

main::regex_sub(438502.pl:40):      print "Code doesn't get run after once.\n";
  DB<1> s
Code doesn't get run after once.
main::regex_sub(438502.pl:41):      my @lengths = ($+[1]);
  DB<1> p scalar @+
5
  DB<2> p scalar @+
3