Discussion on: Daily Challenge #53 - Faro Shuffle

[E. Choroba]

Perl solution. Tests stolen from Donald Feury.

#!/usr/bin/perl
use warnings;
use strict;

sub faro_shuffle {
    my ($deck) = @_;
    die "Odd number of cards.\n" if @$deck % 2;

    my $mid = @$deck / 2;
    return [ map @$deck[$_, $mid + $_], 0 .. $mid - 1 ]
}

use Test::More tests => 5;
use Test::Exception;  

is_deeply faro_shuffle([]), [], 'empty';

is_deeply faro_shuffle(['ace', 'two']), ['ace', 'two'], 'two cards';

is_deeply faro_shuffle(['ace', 'two', 'three', 'four']),
                       ['ace', 'three', 'two', 'four'], 'small deck';

is_deeply faro_shuffle(['ace', 'two', 'three', 'four', 'five', 'six']),
                       ['ace', 'four', 'two', 'five', 'three', 'six'],
                       'original example';

throws_ok { faro_shuffle(['ace', 'two', 'three']) }
    qr/^Odd number of cards\.$/, "odd number exception";