Day 14

lib/aoc2023.ex

@@ -4,12 +4,11 @@ defmodule Aoc2023 do
       import Aoc2023.Common
 
       def main(input) do
-        {took, _} = :timer.tc fn ->
-          parsed = parse(input)
-          IO.puts("Part 1: #{part1(parsed)}")
-          IO.puts("Part 2: #{part2(parsed)}")
-        end
-        IO.puts("Took #{took / 1_000}ms")
+        {t_parse, parsed} = :timer.tc fn -> parse(input) end
+        {t_p1, _} = :timer.tc fn -> IO.puts("Part 1: #{part1(parsed)}") end
+          
+        {t_p2, _} = :timer.tc fn -> IO.puts("Part 2: #{part2(parsed)}") end
+        IO.puts("Took #{(t_parse + t_p1 + t_p2) / 1_000}ms (parse: #{t_parse / 1_000}ms, part1: #{t_p1 / 1_000}ms, part2: #{t_p2 / 1_000}ms)")
       end
     end
   end

lib/day14.ex

@@ -0,0 +1,77 @@
+defmodule Aoc2023.Day14 do
+  use Aoc2023
+
+  def parse(input) do
+    input
+    |> lines
+    |> Enum.map(&String.to_charlist/1)
+  end
+
+  defp replace_many_at(lst, idxs, val) do
+    idxs |> Enum.reduce(lst, &List.replace_at(&2, &1, val))
+  end
+
+  defp slide(grid) do
+    iter = fn recur, grid ->
+      case grid do
+        [last | [next | rest]] ->
+          idxs =
+            last
+            |> Enum.with_index()
+            |> Enum.filter(pipe(elem(0) |> Kernel.==(?O)))
+            |> Enum.map(pipe(elem(1)))
+            |> Enum.filter(&(Enum.at(next, &1) == ?.))
+
+          [
+            last |> replace_many_at(idxs, ?.)
+            | recur.(recur, [next |> replace_many_at(idxs, ?O) | rest])
+          ]
+
+        [last] ->
+          [last]
+      end
+    end
+
+    loop = fn recur, grid ->
+      grid_ = iter.(iter, grid)
+      if grid_ == grid, do: grid, else: recur.(recur, grid_)
+    end
+
+    loop.(loop, grid |> Enum.reverse())
+  end
+
+  defp cycle(grid) do
+    for _ <- 1..4, reduce: grid do
+      # reverse |> transpose is rotation clockwise, but slide already reverses
+      grid -> grid |> slide |> transpose
+    end
+  end
+
+  defp cycles(grid, n \\ 1_000_000_000, {cache_to_n, cache_from_n} \\ {%{}, %{}}) when n > 0 do
+    rep_n = Map.get(cache_to_n, grid)
+    if rep_n do
+      n_ = rep_n - Integer.mod(n, rep_n - n)
+      cache_from_n |> Map.get(n_)
+    else
+      grid_ = cycle(grid)
+      cycles(grid_, n - 1, {Map.put(cache_to_n, grid, n), Map.put(cache_from_n, n, grid)})
+    end
+  end
+
+  def part1(input) do
+    input
+    |> slide
+    |> Enum.with_index(1)
+    |> Enum.map(fn {row, i} -> Enum.count(row, &(&1 == ?O)) * i end)
+    |> Enum.sum()
+  end
+
+  def part2(input) do
+    input
+    |> cycles()
+    |> Enum.reverse
+    |> Enum.with_index(1)
+    |> Enum.map(fn {row, i} -> Enum.count(row, &(&1 == ?O)) * i end)
+    |> Enum.sum()
+  end
+end

lib/mix_tasks.ex

@@ -15,6 +15,7 @@ defmodule Mix.Tasks.Aoc do
   defp module(11), do: Aoc2023.Day11
   defp module(12), do: Aoc2023.Day12
   defp module(13), do: Aoc2023.Day13
+  defp module(14), do: Aoc2023.Day14
   # [MODULE INSERTION POINT]  
 
   defp base_dir(), do: System.get_env("AOC_BASE")
@@ -107,6 +108,10 @@ defmodule Mix.Tasks.Aoc do
     create_file("#{tests_dir(day)}#{last + 1}", IO.read(:stdio, :eof))
   end
 
+  defp run(day, ["test", "expected", test, part, value]) do
+    create_file("#{tests_dir(day)}#{test}.#{part}", value)
+  end
+
   defp run(day, ["test", "expected", test, part]) do
     create_file("#{tests_dir(day)}#{test}.#{part}", IO.read(:stdio, :eof))
   end
@@ -162,6 +167,19 @@ defmodule Mix.Tasks.Aoc do
     run_file(day, "#{base_dir()}/inputs/day#{day}")
   end
 
+  defp run(day, ["run", "submit", part]) do
+    run(day, ["fetch"])
+    mod = module(day)
+    parsed = mod.parse(read("#{base_dir()}/inputs/day#{day}"))
+    val = case part do
+      "1" -> mod.part1(parsed)
+      "2" -> mod.part2(parsed)
+    end
+    HTTPoison.start()
+    resp = HTTPoison.post!("https://adventofcode.com/2023/day/#{day}/answer", {:form, [level: part, answer: stringify(val)]}, "user-agent": "aoc-ex by ben@soroos.net", cookie: "session=#{System.get_env("AOC_SESSION")}")
+    resp |> dbg
+  end
+
   defp run(day, ["run", "-"]) do
     run_file(day)
   end
@@ -209,4 +227,4 @@ defmodule Mix.Tasks.Aoc do
       {:noreply, state}
     end
   end
-end
+end