package DNA;

use strict;
use warnings;

sub new {
    my ($class, $strand) = @_;
    my $self = bless {} => $class;
    $self->{strand} = $strand;
    $self->{len} = length $strand;
    return $self;
}

sub hamming_distance {
    my ($self, $strand) = @_;
    my $distance;
    
    my $len = length $strand;
    $len = $self->{len} if $len > $self->{len};

    my @orig = split // => $self->{strand};
    my @inp  = split // => $strand;

    foreach my $index (0..$len-1) {
        $distance++ if $orig[$index] ne $inp[$index];
    }

    return $distance || 0;
}

__PACKAGE__;