Problem 23

#!/usr/bin/perl
 
use strict;
use warnings;
use POSIX qw(floor);
my %abund_hash;
my @abund_list;
 
foreach my $n (1..28123){
    my $sum = 1;
    foreach (2..floor($n**0.5)){
        if($n % $_ == 0){
                $sum += $_;
                $sum += $n/$_ if (($n/$_) != $_);
        }
    }
    if($sum > $n){
        $abund_hash{$n} = 1;
        push @abund_list, $n;
    }
}
 
 
my $sum = 0;
foreach my $n (1..28123){
    my $i = 0;
    $sum += $n;
    while($n > $abund_list[$i]){
        my $key = $n - $abund_list[$i];
        if($abund_hash{$key}){
                $sum -= $n;
                last;
        }
        $i++;
    }
}
 
print "$sum\n";