my @list = (10,11,12,13,14,15,17,18,22,23,24,25,26,27,28,29,30,31,32,33,34,35 );
my %hash;
@hash{@list} = (1) x @list;

# This solution only makes sense if you're
# making the comparison multiple times
foreach my $x (1..1000)
{
    if ($hash{$x})
    {
       print "$x is in the list\n";
    }
}