adventofcode/2023/07/Part2.pm
2023-12-07 11:10:22 -05:00

69 lines
1.2 KiB
Perl

use 5.38.0;
package Part2;
use Part1;
use List::AllUtils qw/ pairmap sum max /;
use List::UtilsBy qw/ sort_by /;
sub rank_hand(@hand) {
@hand = split '', shift @hand if @hand == 1;
my %group;
$group{$_}++ for @hand;
my $jokers = delete $group{'`'} // 0;
return 7 if 1 >= keys %group;
return 6 if grep { $_+$jokers >= 4 } values %group;
my $max = max values %group;
if( $max + $jokers >= 3 ) {
return 5 if keys %group <= 2;
return 4;
}
return 3 if keys %group == 3;
return 2 if keys %group == 4;
return 1;
}
sub handify($str) {
state %map = (
'T' => 10,
'J' => 1,
'Q' => 12,
'K' => 13,
A => 14
);
my @cards = map { chr( ord('a') + $_ - 2 )} map { $map{$_} // $_ } split '', $str;
return \@cards;
}
sub parse_input($input) {
my @lines = split "\n", $input;
my @hand_score = pairmap {
[ handify($a), $b]
} map { split " " } @lines;
return @hand_score;
}
sub score(@hand) {
join '', rank_hand(@hand), @hand;
}
sub solution_2 ($input) {
my @hand_score = sort_by { score($_->[0]->@*) } parse_input($input);
my $rank = 0;
return sum map { ++$rank * $_->[1] } @hand_score;
}
1;