#!/usr/bin/perl
use warnings;
use strict;
use Data::Dumper;
########

sub three_digit_prodcuts {
    my @products = ();
    my $i = 999;
    my $counter = 999;
    while ($i >= 100 ) {
	  my $product = $i * $counter;
	  push @products, $product;
	  $counter--;
	  if ($counter >= 100) {
	      redo;
	  }else {
	      $counter = $i - 1;
	      $i--;
	      next;
	  }
    }

      return \@products;
}

my $pr =  three_digit_prodcuts;
my @arr = ();
foreach my $n (@$pr) {
    my $rev = join '', reverse(split //, $n);
    if ($n == $rev) {
	    push @arr, $n;
        next;
    }
}

my $largest =  ( sort { $b <=> $a } @arr)[0];
print "$largest\n";

$ time ./largest_3_digit_product_palindrome.pl
906609

real	0m0.633s
user	0m0.614s
sys	0m0.018s