To sum a list, I used the sum from List::Util. I made the following observation: if the array can be split, then the sum of each part is the half of the sum of the whole array. I used vec to generate binary vectors to be used as Indicator function. Checking a half of the possible vectors is enough, the rest is complementary (i.e. the two subsets are swapped).

#!/usr/bin/perl
use warnings;
use strict;

use List::Util qw(sum);


sub is_divisible {
    my $array = shift;
    my $sum   = sum(@$array) / 2;

    for my $bitmask (1 .. 2 ** $#$array - 1) {
        return 1 if sum(map { $array->[$_] * vec $bitmask, $_, 1} 0 ..
+ $#$array) == $sum;
    }

    return;
}



my @arrays = (
              [qw(1 3 5 7)],
              [qw(1 3 8 4)],
              [qw(1 6 2)],
              [qw(5 5 4 6 2 8 1 9)],
             );

for my $array (@arrays) {
    print "@$array: ", is_divisible($array) ? 'yes' : 'no', "\n";
}
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