2022 AoC Day 3 – Rucksack Reorganization

This is a solution to Advent of Code 2022 day 3, written in Raku.

https://adventofcode.com/2022/day/3

Part One

Find the item type that appears in both compartments of each rucksack. What is the sum of the priorities of those item types?

my @rucksacks = '3-input.txt'.IO.lines.map({
    my @contents = .comb;
    my Int $half = +@contents div 2;
    my @i = [(&)] @contents[^$half, $half..*];
    given @i.head.key {
        when / <[a..z]>/ { $_.ord - 'a'.ord + 1 }
        when / <[A..Z]> / { $_.ord - 'A'.ord + 27 }
    }
});
say [+] @rucksacks;

Part Two

Find the item type that corresponds to the badges of each three-Elf group. What is the sum of the priorities of those item types?

my @groups = '3-input.txt'.IO.lines.map({ .comb }).map(-> @a, @b, @c, {
    my $i = (@a (&) @b (&) @c).head.key;
    given $i {
        when / <[a..z]>/ { $_.ord - 'a'.ord + 1 }
        when / <[A..Z]> / { $_.ord - 'A'.ord + 27 }
    }
});
say [+] @groups;

raku