# however, these assume strings don't contain \0

sub lcp_v4 {
    my ($e, $s) = ("", @_);
    $e |= $_ ^ $s for @_;
    $e =~ m/^\0*/;
    substr($s, 0, $+[0]);
}

sub lcp_v5 {
    my ($a, $b) = (sort @_)[0,-1];
    ($a ^ $b) =~ m/^\0*/;
    substr($a, 0, $+[0]);
}

use List::Util qw(minstr maxstr);
sub lcp_v6 {
    my ($a, $b) = (&minstr, &maxstr);
    ($a ^ $b) =~ m/^\0*/;
    substr($a, 0, $+[0]);
}