Day 6 - Advent of Code 2016

lib/advent_of_code/2016/day-06.livemd

Tyler Johnson

@tylerj

aoc

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Day 6 - Advent of Code 2016

Mix.install([:kino, :benchee])

:ok

Prompt

--- Day 6: Signals and Noise ---

Something is jamming your communications with Santa. Fortunately, your signal is only partially jammed, and protocol in situations like this is to switch to a simple repetition code to get the message through.

In this model, the same message is sent repeatedly. You've recorded the repeating message signal (your puzzle input), but the data seems quite corrupted - almost too badly to recover. Almost.

All you need to do is figure out which character is most frequent for each position. For example, suppose you had recorded the following messages:

eedadn
drvtee
eandsr
raavrd
atevrs
tsrnev
sdttsa
rasrtv
nssdts
ntnada
svetve
tesnvt
vntsnd
vrdear
dvrsen
enarar

The most common character in the first column is e; in the second, a; in the third, s, and so on. Combining these characters returns the error-corrected message, easter.

Given the recording in your puzzle input, what is the error-corrected version of the message being sent?

To begin, get your puzzle input.

--- Part Two ---

Of course, that would be the message - if you hadn't agreed to use a modified repetition code instead.

In this modified code, the sender instead transmits what looks like random data, but for each character, the character they actually want to send is slightly less likely than the others. Even after signal-jamming noise, you can look at the letter distributions in each column and choose the least common letter to reconstruct the original message.

In the above example, the least common character in the first column is a; in the second, d, and so on. Repeating this process for the remaining characters produces the original message, advent.

Given the recording in your puzzle input and this new decoding methodology, what is the original message that Santa is trying to send?

Although it hasn't changed, you can still get your puzzle input.

Input

input = Kino.Input.textarea("Please paste your input file:")

input = input |> Kino.Input.read()

"bgpmxqws\nmxvdaluh\nwpgcrcix\ndjugxgak\nurjgbqde\nvcsylkay\nruyowwjt\neepdbfaa\nkpzjujdv\nilsbjxbf\nxljdcdpc\nvnmtqzbu\ndsiruyjs\noemrvmqj\nbunqbyjw\nwixyxnwq\ntfmpgyen\nrxjphoyf\nkeohkpwv\ngbpfqodg\npalgwnye\nzzriwene\nwmczggbk\nxikxduml\nestibkpk\nivcghhot\nuvczidij\nqmdmpfxn\nxjgypmry\nxwzgzxeu\nejvoqgyr\nqzbnawul\nmhtvpsma\nvzddmtyx\nckhdphcd\nrrxiqrqd\ntdnauotp\nzsoqslob\noxbleyra\ndfspawmw\namewbjnz\ndhryqzsg\ngevzondd\ngjtlhacs\nywoghawg\nxgiglflw\njlfewwky\nxvhjgvhk\nbaocvjcl\nwnweoaib\nuepsdnur\nvmynttbb\naoqezdgl\noahtcpli\nhixokbhp\nrsdwsjnv\nnqckpjlt\njksheyvr\nasabcisr\njirzozrt\njypcypek\nhbeimsej\nvzwnchwy\nozjqqyaz\nhbxcqvne\nyfmthknj\nyxicfnav\nfhfwaetl\nlyhvemqr\nkyyzkgfb\nunigfcbx\njyszsjto\nqoomixgp\nvwqlvanp\nwteqnjhj\ndtcfvira\nwztxowzh\nrjuayajd\nmcvaqelp\nwazbrrej\nqwuiszub\nfohaxlyl\nvizomswk\npkjhxghs\nxhygtcbp\ngrzjvlas\ntgssuvej\njypumznm\nymiymxbk\nfdnhxmpc\nnqwlpigo\necpyhmgw\nhbxpvgoh\npkflsrjo\nzrjugqge\njwvlowtd\nmkslbbql\nhsektxsi\npsanaqop\nylorypou\ntkfircdx\nftkfzmno\nrdasheam\neulndcvo\ngpetuqvl\nfelsxwks\nxckkdvyc\nnlbymfrt\ngcqxmyse\ngbbnguow\ncdaduwiv\nsqikwrbi\nppwteldh\ntyurlqsr\noogkdood\nslxekxkj\ntunmorwo\nmphktfgp\nylkifdek\nbyopdakn\nzgpqnghe\nlltqwxuf\npalhjqcb\nxxrbywel\nxolycxlx\nbkiimxvx\nhtztessk\naamwgfrm\nextuovqh\nbpkmstaf\nhazuzhkf\ncjiqycqs\nsxafxxpp\nmtfowzth\npoosymcj\nvbykdleq\nbxhhfyak\nkbyminxs\ngviprbxv\nbqxhjffd\nwmuwlzoy\niwazluuu\nuhwxfelq\ngfvqwfgj\nuqvyjkgr\neanwjhhl\nizpooten\ngkqhaiel\njforeagg\nhrqjylmb\nkcvfbohb\njkoskwff\nymuqatcy\nnaeceeru\nalghunmu\nygsgeyxy\nfhsxqtsx\niikldgzj\nzwsdownm\nsvbdvddw\nujwdwmju\npuszwwxg\npwzuivlo\nnoqjcwqu\nlsnvidsn\nrhuvjosk\nrxktxanu\niftbsfjc\nkgrxrkwl\nrfzknqde\nafqcjguq\nsghybsrn\nqtipzcwy\nyyqhuufw\nzaeukrhr\nrqtlcflu\nridxvnur\nwcxzmvka\npqxcddgq\neetnhsux\nkblokhxx\nbmctwlgo\ncpojyilz\nyhnmkhjp\nbtudgpci\nmzvjtlhh\nxabfbuvt\njgoltfpy\ngsjdsaco\nbmxhpnri\nncdkduzl\njhzyshfz\nqhruewva\ncgkafvvm\nntjbaria\nrpfxuhht\nwnqbudow\nbcezvcpt\nnqrhgrkn\ntceyjrqf\npyszfamz\nnctlttmt\nbvhanhoc\nilffiatn\nfwmskxwg\nvezsripn\nhbjxpdyd\ntjnpgdib\ntiuniqdj\nmrzlrnmn\nngqrtjxr\neoyorrfy\nrtkidptz\nzwglnkeu\nanjcxsgc\ndbuotxcq\nsqpsxbmt\nczyxgtcv\nojhmhssl\nlfbhgnox\npecipazx\nnvcfxguk\ngdniujcm\ntcdfhgez\nzxzybtvb\noddtlvmw\nvxdcfivs\nldgbhriu\nlcuccuup\ndwzyuvkh\npdoomnps\njfaqworq\nzfeecwuy\nzxytmbzh\niuzcfqac\nkxvxqpam\ngyfryaqu\ndusowjue\nuwrofbxz\njwhbtsgg\ntjpubrqi\nvncupbao\nlbusnztb\nkbpkhcau\nprrcxgti\naflcpnsq\nxtspjvwl\nfqjgujib\ntnlahhpp\nboovsuro\neytzygmd\nvdyysubn\nsyxcupva\nulgjkkdy\npzhevrme\nvynmztwh\nwrwebmrb\npdfniopo\nnnusdprq\nqzrnxboz\nfhvnyafq\nisbzhjnq\nnxfvcxvy\niuzgpevj\napjpvsdk\nunltokdk\nneccyyrf\ngkkafbth\nudnurvso\ngzosdaws\nsnetsjdd\nzcsgluqb\nfdsvyiho\nkjvmexiu\nugfpphts\ndbkvkdok\ndrpkejfw\nlwyshtxq\nqilaojzn\nqilwixhi\nhbuzdkgg\namdettxe\nrilvspmg\ncyvfwmwg\nkqbmwvvi\nnuxdfinf\nozfvzigf\nvhjvfosm\nvfmgntex\ncswjzkft\nkvqqlvbh\nppwpiqcb\nwewsncdj\nndkjslvd\nlivwaogi\nslupeobk\nchvlbixa\noprvhtpn\nwrgwrzic\nmeyhlwzr\nwcwplger\ncfdwqikc\nvokgnzjv\nsxmxzlwh\nrttwwsrg\napqmweoc\nxcrgliqw\negjenpzi\nuuaoghhw\nubaubqir\nslxfrqfz\nuooravpz\njukdeivx\nqvelgzzi\nzbcnzjsj\nnoivjeht\ntomkyktn\nowixssbg\nqrjikjok\nopieopkj\nhzrratbf\ntawhmgiz\nzojlupqh\niuxrcduy\ngxdvgzke\ntcsqiada\noqanfwxs\nhoeavozw\nkteefzjp\nxjepfoho\nacaimhfz\nifeqkbqc\nszwlvqwc\njrtfkzxv\naqgmlcyg\nstsejxzs\nmukbwojc\nyorhqkqz\nqgkehpbu\nqrpealli\nmcwerdgx\nvqxkeyqe\npmstbkfy\nuriiqytq\npuyrfebm\ncljqpflg\nyhjxqfee\nwvyitlyj\nstvxunze\nsurpasjh\nlaqbwefs\ntmhzxhcp\nxnrmdgci\ncvoziimt\ndbeqiwio\nbncszppp\nwajpsycd\nncmrinrp\nzsctcqzy\nvkfwzoda\nzeturmnd\ndydeylro\ngggkrwzw\noobmkfhz\nvimgaxkq\ncuftcyxg\njzczmzab\njqvvaljj\nfvlbbduo\ntvoipipg\nihdqovcz\nfhylllit\nwngiyeld\npanifluc\nnariaulb\nuiqpccns\nvdeevhcb\nfjddbcfa\nnymgtdmf\nqvkrocra\nlelplbmu\nqwajtxne\ncjgljjwm\nkdyecbii\nrmhccint\nmeclgocv\nahvvcbck\nuktuwuag\ndcnpzwjn\nigfbtmnr\nwdioghpd\nkeuuecam\nclxwiylf\noqsbygex\ndbxhlukg\nrkxjjlvn\nvotomymd\nhqyfigpr\nqnuvattu\nflrxtbsl\nzinwdott\nwxpzgsxk\nglvwrzqv\nasruvcjq\naanwzupj\nkrbxlowc\nnfbrzogr\nivvbjgyt\nmxbuttye\nrhzksroq\nskipgtsv\nwrfnmsgm\nckdgipqw\nuxbylsdi\nbazhagcz\nmelrnxrj\nqqqoyhqf\nhrfjpsrx\nhafnvrdg\nwzasinyu\nfrbkqlzq\npkpasbfh\nuaadlrys\ntjxovpar\nlvqxahjd\nereefqow\ntmwalbhi\neflnfinc\nhwmxucjt\niedrvuyy\nmnmxdbhv\nqghmvftt\nboqbamap\nrjfncukp\njsyshihy\nkwfcnspx\nlsvaiysm\nxlypkceq\nuvpxfarx\nonktnulb\ncrycggor\nhzntxzxs\njodwwaaj\nasmnoijg\nlkgabxtn\nyinohytm\ncymfafvu\npfwnxkga\nfcaepans\ndrpzqntz\ndmtlraxa\nxpuaeobo\nnpwbdnyw\nprgddqif\ncfjaozss\ny" <> ...

Solution

defmodule Day06 do
  defdelegate parse(input), to: __MODULE__.Input

  def part1(input) do
    input
    |> parse()
    |> List.zip()
    |> Enum.map(&Tuple.to_list/1)
    |> Enum.map(&Enum.frequencies/1)
    |> Enum.map(&Enum.max_by(&1, fn {_, v} -> v end))
    |> Enum.map(&elem(&1, 0))
    |> Enum.join("")
  end

  def part2(input) do
    input
    |> parse()
    |> List.zip()
    |> Enum.map(&Tuple.to_list/1)
    |> Enum.map(&Enum.frequencies/1)
    |> Enum.map(&Enum.min_by(&1, fn {_, v} -> v end))
    |> Enum.map(&elem(&1, 0))
    |> Enum.join("")
  end

  defmodule Input do
    def parse(input) when is_binary(input) do
      input
      |> String.split("\n", trim: true)
      |> parse()
    end

    def parse(input) when is_list(input) do
      Enum.map(input, &parse_line/1)
    end

    def parse_line(line) do
      String.split(line, "", trim: true)
    end
  end
end

{:module, Day06, <<70, 79, 82, 49, 0, 0, 12, ...>>,
 {:module, Day06.Input, <<70, 79, 82, ...>>, {:parse_line, 1}}}

Given the recording in your puzzle input, what is the error-corrected version of the message being sent?

Your puzzle answer was qqqluigu.

Day06.part1(input)

"qqqluigu"

Given the recording in your puzzle input and this new decoding methodology, what is the original message that Santa is trying to send?

Your puzzle answer was lsoypmia.

Day06.part2(input)

"lsoypmia"

Both parts of this puzzle are complete! They provide two gold stars: **

At this point, you should return to your Advent calendar and try another puzzle.

If you still want to see it, you can get your puzzle input.

Tests

ExUnit.start(auto_run: false)

defmodule Day06Test do
  use ExUnit.Case, async: false

  setup_all do
    [
      input:
        "eedadn\ndrvtee\neandsr\nraavrd\natevrs\ntsrnev\nsdttsa\nrasrtv\nnssdts\nntnada\nsvetve\ntesnvt\nvntsnd\nvrdear\ndvrsen\nenarar"
    ]
  end

  describe "part1/1" do
    test "returns expected value", %{input: input} do
      assert Day06.part1(input) == "easter"
    end
  end

  describe "part2/1" do
    test "returns expected value", %{input: input} do
      assert Day06.part2(input) == "advent"
    end
  end
end

ExUnit.run()

..
Finished in 0.00 seconds (0.00s async, 0.00s sync)
2 tests, 0 failures

Randomized with seed 336999

%{excluded: 0, failures: 0, skipped: 0, total: 2}

Benchmarking

# https://github.com/bencheeorg/benchee

Benchee.run(%{
  "Part 1" => fn -> Day06.part1(input) end,
  "Part 2" => fn -> Day06.part2(input) end
})

nil

Operating System: macOS
CPU Information: Apple M1
Number of Available Cores: 8
Available memory: 8 GB
Elixir 1.14.2
Erlang 25.1.2

Benchmark suite executing with the following configuration:
warmup: 2 s
time: 5 s
memory time: 0 ns
reduction time: 0 ns
parallel: 1
inputs: none specified
Estimated total run time: 14 s

Benchmarking Part 1 ...
Benchmarking Part 2 ...

Name             ips        average  deviation         median         99th %
Part 1        618.44        1.62 ms     ±4.96%        1.62 ms        1.79 ms
Part 2        604.22        1.66 ms     ±4.75%        1.66 ms        1.83 ms

Comparison: 
Part 1        618.44
Part 2        604.22 - 1.02x slower +0.0381 ms