adventofcode/2023/08/Part2.pm
2023-12-09 13:04:13 -05:00

92 lines
2.0 KiB
Perl

use 5.38.0;
package Part2;
use Part1;
use List::AllUtils qw/all first_index none min max /;
sub get_cycle( $current, $directions, $nodes ) {
my @tracks;
my $next_index = 0;
while() {
use DDP; #p @tracks;
my $t = join '-', $current,$next_index;
my $i = first_index { $_ eq $t } @tracks;
if( $i > -1 ) {
my $c = 0;
# p @tracks;
# warn $i, " ",$t;
return $i, map {
$c++;
if(/Z-/) {
my $x = $c; $c = 0; $x;
}else {
()
}
} splice @tracks, $i;
}
push @tracks, $t;
$current = $nodes->{$current}[ $directions->[ $next_index ] ];
$next_index = ( $next_index+1)% @$directions;
}
}
sub solution_2 ($input) {
my $p = Part1::parse_input($input);
my @directions = $p->{directions}->@*;
my %nodes = $p->{nodes}->%*;
my @paths;
my @initial = grep { /A$/ } keys %nodes;
for (@initial ) {
push @paths, [
Part2::get_cycle($_,\@directions,\%nodes)
];
}
my $visited = 0;
my @preloop = map { shift @$_ } @paths;
p @preloop;
my $pre = max @preloop;
$visited += $pre;
my @current = map { $preloop[$_] - $pre } 0..$#preloop;
p @current;p @paths;
for(0..$#current) {
while( $current[$_] <= 0 ) {
$current[$_] += $paths[$_][0];
push $paths[$_]->@*, shift $paths[$_]->@*;
}
}
p @current;p @paths;
until( none { $_ } @current ) {
use DDP;
warn $visited;
p @current;p @paths;
my $incr = max @current;
warn $incr;
$visited += $incr;
for ( 0..$#current) {
$current[$_] -= $incr;
while( $current[$_] < 0 ) {
$current[$_] += $paths[$_][0];
push $paths[$_]->@*, shift $paths[$_]->@*;
}
}
}
return $visited;
}
1;
1;