adventofcode/2017/24/2.pl

37 lines
780 B
Perl

use 5.20.0;
use experimental qw/ signatures postderef smartmatch /;
use List::AllUtils qw/ sum max first_index min/;
my @elements = map { chomp; [ split '/' ] } <>;
use DDP;
my $inv_length = 1E99;
my $max = 0;
build_bridge(0,0,@elements);
say $max;
sub build_bridge( $sofar = 0, $connector = 0, @left ) {
for my $i ( 0..$#left ) {
next unless $connector ~~ $left[$i]->@*;
my @copy = @left;
my $i = splice @copy, $i, 1;
my $next_con = $i->[ 1 - first_index { $_ == $connector } @$i ];
build_bridge( $sofar + sum( @$i ), $next_con, @copy );
}
return if @left > $inv_length;
if( @left == $inv_length ) {
$max = max $max, $sofar;
}
else {
$inv_length = @left;
$max = $sofar;
}
}