[Solved] Perl find the elements that appears once in an array

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This is a variation on perlfaq5 – How can I remove duplicate elements from a list or array?

Just use a hash to count the elements, and then print the ones seen only once.

use strict;
use warnings;

my @array = qw(18 1 18 3 18 1 1 2 3 3);

my @nondup = do {
    my %count;
    $count{$_}++ for @array;
    grep {$count{$_} == 1} keys %count;
};

print "@nondup\n";

Outputs:

2

2

solved Perl find the elements that appears once in an array