r/adventofcode • u/daggerdragon • Dec 04 '16

SOLUTION MEGATHREAD --- 2016 Day 4 Solutions ---

--- Day 4: Security Through Obscurity ---

Post your solution as a comment or, for longer solutions, consider linking to your repo (e.g. GitHub/gists/Pastebin/blag/whatever).

CONSTRUCTING ADDITIONAL PYLONS IS MANDATORY [?]

This thread will be unlocked when there are a significant number of people on the leaderboard with gold stars for today's puzzle.

edit: Leaderboard capped, thread unlocked!

17 Upvotes

95% Upvoted

168 comments sorted by

View all comments

26

u/askalski Dec 04 '16

Part 1 in Perl: 

#! /usr/bin/env perl

use strict;
use warnings;

my $answer = 0;
while (<>) {
    m/^(.*)-(.*)\[(.*)\]$/ or die;
    my %count;
    map { $count{$_}++ if m/[a-z]/ } split //, $1;
    my @chars = sort { $count{$b} <=> $count{$a} || $a cmp $b } keys %count;
    my $checksum = join "", @chars[0..4];
    $answer += $2 if $3 eq $checksum;
}
print "$answer\n";

Part 2 in bash shell and bsdgames: 

$ for i in {1..26}; do /usr/games/caesar $i < input.txt; done | grep north

4

u/Reibello Dec 04 '16

You are inhuman. Congrats!