aoc

sol1.pl (648B) [raw]

---

 #!/usr/bin/env perl
 use strict;
 use warnings;
 
 my $preamble = 25;
 my $n = 0;
 my @mem;
 while (my $l = <ARGV>) {
     chomp $l;
     if ($n < $preamble) {
         # build memory
         push (@mem, $l);
         $n++;
     } else {
         # use memory
         check($l, \@mem);
         shift(@mem);
         push(@mem, $l);
     }
 }
 exit 1;
 
 sub check {
     my ($l, $memA) = @_;
 
     # TODO: optimize?
     my %seen;
     for my $m (@$memA) {
         $seen{$m} = 1;
         my $c = $l - $m;
         if ($seen{$c} && $c != $m) {
             # success!
             return;
         }
     }
 
     # nothing adds up! report & exit
     print "$l\n";
     exit 0;
 }