adventofcode/2020/13/part2.pm

55 lines
912 B
Perl
Raw Normal View History

2021-12-05 16:51:21 +00:00
package part2;
use 5.20.0;
use warnings;
use List::AllUtils qw/ min max /;
use POSIX qw/ ceil /;
require './part1.pm';
use experimental qw/ signatures postderef /;
sub find($t, $next=undef, @buses) {
return 0 unless $next;
if( $next eq 'x' ) {
return find($t+1, @buses );
}
my $n = $t / $next;
my $nint = int $n;
if( $nint == $n ) {
return find( $t+1, @buses );
}
return (1+$nint)*$next;
}
sub solution(@buses) {
@buses = map { $_ eq 'x'?1:$_
} @buses;
my $t = 1;
T: while() {
my $i = 0;
my @min = map {
my $s = $t + $i++;
$_ * ceil($s/$_);
} @buses;
warn join " ", @min;
for(0..$#min-1) {
if( $min[$_] != $min[$_+1]-1 ) {
$t = max map { $min[$_] - $_ } 0..$#min;
next T;
}
}
return $t;
}
}
1;