Advent of code, day 1

day1.pl6

# The captcha requires you to review a sequence of digits (your puzzle input)
# and find the sum of all digits that match the next digit in the list. The
# list is circular, so the digit after the last digit is the first digit in
# the list.

# For example:

# 1122 produces a sum of 3 (1 + 2) because the first digit (1) matches the second digit and the third digit (2) matches the fourth digit.
# 1111 produces 4 because each digit (all 1) matches the next.
# 1234 produces 0 because no digit matches the next.
# 91212129 produces 9 because the only digit that matches the next one is the last digit, 9.

my $test = "1122";

sub seq_sum($digits) {
    # Seems like there should be a nicer way to do this conversion
    my @d = $digits.split('')[1..$digits.chars];
    my @n = @d.rotate(1);

    (@d Z @n).grep(-> ($a, $b) { $a == $b })
        .map({.first})
        .sum
        .say
}

seq_sum($test)