Tour de 14er Calculations

#!/usr/bin/perl 

use DateTime;

my $start_str = '05:11:43 AM (MDT) 07/26/16';
my $end_str   = '02:58:07 PM (MDT) 08/10/16';
my $num_14ers = 27;

my $start = parse_trackleaders_str($start_str);
my $end   = parse_trackleaders_str($end_str);

my $start_dt = DateTime->new($start);
my $end_dt   = DateTime->new($end);

my $dur = $start_dt->subtract_datetime_absolute($end_dt);

my $per_days_sec = int( $dur->seconds ) / $num_14ers;
print formatted_runtime( $dur->seconds ) . "\n";
print 'Summiting a 14er every, ' . formatted_runtime($per_days_sec) . "\n";
print sprintf( "%.2f", ( 86400 / $per_days_sec ) ) . ' 14ers/day';

sub parse_trackleaders_str {
    my $str = shift;
    my $d   = {};
    ( $d->{time}, $d->{tod}, $d->{time_zone}, $d->{date} ) =
      split( ' ', $str, 4 );
    ( $d->{hour},  $d->{minute}, $d->{second} ) = split( ':', $d->{time}, 3 );
    ( $d->{month}, $d->{day},    $d->{year} )   = split( '/', $d->{date}, 3 );

    if ( $d->{tod} eq 'PM' ) {
        $d->{hour} = int( $d->{hour} ) + 12;
    }

    #$d->{time_zone} =~ s/\(|\)//g;
    $d->{time_zone} = 'local';    # uh, hack. I'm in Colorado!
    delete( $d->{date} );
    delete( $d->{time} );
    delete( $d->{tod} );

    return $d;

}

sub formatted_runtime {

    my $d = shift || 0;

    my @int = (
        [ 'second', 1 ],
        [ 'minute', 60 ],
        [ 'hour',   60 * 60 ],
        [ 'day',    60 * 60 * 24 ],
        [ 'week',   60 * 60 * 24 * 7 ],
        [ 'month',  60 * 60 * 24 * 30.5 ],
        [ 'year',   60 * 60 * 24 * 30.5 * 12 ]
    );
    my $i = $#int;
    my @r;
    while ( ( $i >= 0 ) && ($d) ) {
        if ( $d / $int[$i]->[1] >= 1 ) {
            push @r, sprintf "%d %s%s", $d / $int[$i]->[1],
              $int[$i]->[0], ( sprintf "%d", $d / $int[$i]->[1] ) > 1
              ? 's'
              : '';
        }
        $d %= $int[$i]->[1];
        $i--;
    }
    my $runtime;
    if (@r) {
        $runtime = join ", ", @r;
    }
    else {
        $runtime = '0 seconds';
    }

    return $runtime;
}