use strict;
use warnings;

package RangeMap;

# Credit: Aristotle Pagaltzis!

sub new($$$) {
	my $class      = shift;
	my $max_length = shift;
	my $ranges_a = shift;
	my @lookup;
	for (@{$ranges_a}) {
		my ( $start, $end ) = @$_;
		my @idx
			= $end >= $start
			? $start .. $end
			: ( $start .. $max_length, 1 .. $end );
		for my $i (@idx) { $lookup[$i] .= pack 'L', $end }
	}
	bless \@lookup, $class;
}

sub num_ranges_containing($$$) {
	my $self = shift;
	my ( $start, $end ) = @_;
	return 0 unless (defined $self->[$start]);
	return 0 + grep { $end <= $_ } unpack 'L*', $self->[$start];
}

1;