adventofcode/2023/07/Part1.pm

use 5.38.0;

package Part1;

use List::AllUtils qw/ pairmap sum /;
use List::UtilsBy  qw/ sort_by /;

sub rank_hand (@hand) {
    @hand = split '', shift @hand if @hand == 1;

    my %group;
    $group{$_}++ for @hand;

    return 7 if 1 == keys %group;

    return 6 if grep { $_ == 4 } values %group;

    if( grep { $_ == 3 } values %group ) {
        return 5 if keys %group == 2;
        return 4;
    }

    return 3 if keys %group == 3;

    return 2 if keys %group == 4;

    return 1;
}

sub handify ($str) {
    state %map = (
        'T' => 10,
        'J' => 11,
        'Q' => 12,
        'K' => 13,
        A   => 14
    );

    return [
      map { chr( ord('a') + $_ - 2 ) } map { $map{$_} // $_ } split '', $str
      ];
}

sub parse_input ($input) {
    return pairmap {
        [ handify($a), $b ]
    }
    map { split " " } split "\n", $input;
}

sub score (@hand) {
    join '', rank_hand(@hand), @hand;
}

sub solution_1 ($input) {
    my $rank       = 0;
    return sum map { ++$rank * $_->[1] } sort_by { score( $_->[0]->@* ) } parse_input($input);
}

1;