use strict;
use warnings;

sub samefringe {
	my ($x, $y) = @_;
	my ($ix, $iy) = (0,0);
	samefringe_r($x, $y, $ix, $iy) and $#{$x}+1 == $ix and $#{$y}+1 == $iy;
}

sub samefringe_r {
	my ($x, $y, $ix, $iy) = @_;

	while ($ix <= $#{$x} and $iy <= $#{$y}) {
		if (ref($x->[$ix])) {
			my $i_ix = 0;
			samefringe_r( $x->[$ix], $y, $i_ix, $iy) or return;
			$ix++;
		} elsif (ref($y->[$iy])) {
			my $i_iy = 0;
			samefringe_r( $x, $y->[$ix], $ix, $i_iy) or return
			$iy++;
		} elsif ($x->[$ix] ne $y->[$iy]) {
			return
		} else {
			$ix++;
			$iy++;
		}
	}
	$_[2]=$ix;$_[3]=$iy;
	return 1;
}

my $l1 = [ "a", [qw(b c)], "d" ];
my $l2 = [ qw(a b c d) ];
my $l3 = [ qw(a b c d e)];
my $l4 = [ qw(a x c d)];

print "1 x 2, should be same : ".(samefringe($l1, $l2) ? 'same' : 'diff')."\n";

print "1 x 3, should be diff : ".(samefringe($l1, $l3) ? 'same' : 'diff')."\n";
print "1 x 4, should be diff : ".(samefringe($l1, $l4) ? 'same' : 'diff')."\n";
print "2 x 3, should be diff : ".(samefringe($l2, $l3) ? 'same' : 'diff')."\n";
print "2 x 4, should be diff : ".(samefringe($l2, $l4) ? 'same' : 'diff')."\n";