adventofcode/2017/06/2.pl

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Perl
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2017-12-06 16:50:31 +00:00
use 5.20.0;
use experimental 'postderef';
use List::UtilsBy qw/ max_by/;
my @stacks = split ' ', <>;
my %seen;
until( $seen{ join ':', @stacks }++ ) {
redistribute();
}
my $target = join ":", @stacks;
my $i = 0;
redistribute($i++) until $i and $target eq join ':', @stacks;
say $i;
sub redistribute {
warn "@stacks\n";
my $col = max_by { $stacks[$_] } 0..$#stacks;
my $v = $stacks[$col];
$stacks[$col] = 0;
$stacks[ ++$col % @stacks ]++ while $v--;
}