From 4420dfa522838f7fc09f8a0b9307880a77731e1e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Anders=20Ytterstr=C3=B6m?= <yttan@fastmail.se>
Date: Mon, 12 Dec 2022 14:27:16 +0100
Subject: [PATCH] Add solutions for 2022:10 "Cathode-Ray Tube"

---
 2022-elixir/lib/solutions/day_10.ex        |  84 ++++++++++
 2022-elixir/test/solutions/day_10_test.exs | 171 +++++++++++++++++++++
 2 files changed, 255 insertions(+)
 create mode 100644 2022-elixir/lib/solutions/day_10.ex
 create mode 100644 2022-elixir/test/solutions/day_10_test.exs

diff --git a/2022-elixir/lib/solutions/day_10.ex b/2022-elixir/lib/solutions/day_10.ex
new file mode 100644
index 0000000..3b9247d
--- /dev/null
+++ b/2022-elixir/lib/solutions/day_10.ex
@@ -0,0 +1,84 @@
+defmodule Aoc.Solution.Day10 do
+  import Aoc.Utils
+
+  @name "Day 10: Cathode-Ray Tube"
+  @behaviour Solution
+
+  @impl Solution
+  def get_name, do: @name
+
+  @impl Solution
+  def present(solution), do: "Sum of signal strengths is #{solution}"
+
+  @impl Solution
+  def present_again(solution), do: "The 8 capital letters appearing on CRT:\n\n#{solution}"
+
+  @impl Solution
+  def parse!(raw) do
+    raw |> split_lines()
+  end
+
+  @impl Solution
+  def solve(program) do
+    {snapshots, _} = cycle(program)
+    Enum.sum(snapshots)
+  end
+
+  @impl Solution
+  def solve_again(program) do
+    {_, pixels} = cycle(program)
+
+    pixels
+    |> Enum.reverse()
+    |> Enum.chunk_every(40)
+    |> Enum.map(fn l ->
+      Enum.join(l, "")
+    end)
+    |> Enum.join("\n")
+  end
+
+  def cycle(program), do: cycle(1, program, program)
+
+  def cycle(x, instructions, program, snapshots \\ {[], []}, queue \\ [], ticks \\ 1)
+
+  def cycle(_x, _instructions, _program, snapshots, _queue, 241) do
+    snapshots
+  end
+
+  def cycle(x, [], program, snapshots, queue, ticks) do
+    cycle(x, program, program, snapshots, queue, ticks)
+  end
+
+  def cycle(x, instructions, program, snapshots, [v | queue], ticks) do
+    cycle(x + v, instructions, program, log(snapshots, ticks, x), queue, ticks + 1)
+  end
+
+  def cycle(x, ["noop" | instructions], program, snapshots, queue = [], ticks) do
+    cycle(x, instructions, program, log(snapshots, ticks, x), queue, ticks + 1)
+  end
+
+  def cycle(x, ["addx " <> v | instructions], program, snapshots, queue = [], ticks) do
+    cycle(
+      x,
+      instructions,
+      program,
+      log(snapshots, ticks, x),
+      [String.to_integer(v) | queue],
+      ticks + 1
+    )
+  end
+
+  def log({snapshots, pixels}, ticks, x) when ticks in [20, 60, 100, 140, 180, 220] do
+    {[ticks * x | snapshots], lit(pixels, ticks, x)}
+  end
+
+  def log({snapshots, pixels}, ticks, x) do
+    {snapshots, lit(pixels, ticks, x)}
+  end
+
+  def lit(pixels, pos, x) when rem(pos - 1, 40) in (x - 1)..(x + 1) do
+    ["#" | pixels]
+  end
+
+  def lit(pixels, _pos, _x), do: ["." | pixels]
+end
diff --git a/2022-elixir/test/solutions/day_10_test.exs b/2022-elixir/test/solutions/day_10_test.exs
new file mode 100644
index 0000000..22354bf
--- /dev/null
+++ b/2022-elixir/test/solutions/day_10_test.exs
@@ -0,0 +1,171 @@
+defmodule Day10Test do
+  use ExUnit.Case
+  doctest Aoc.Solution.Day10
+  import Aoc.Solution.Day10
+
+  @input ~s(
+    addx 15
+    addx -11
+    addx 6
+    addx -3
+    addx 5
+    addx -1
+    addx -8
+    addx 13
+    addx 4
+    noop
+    addx -1
+    addx 5
+    addx -1
+    addx 5
+    addx -1
+    addx 5
+    addx -1
+    addx 5
+    addx -1
+    addx -35
+    addx 1
+    addx 24
+    addx -19
+    addx 1
+    addx 16
+    addx -11
+    noop
+    noop
+    addx 21
+    addx -15
+    noop
+    noop
+    addx -3
+    addx 9
+    addx 1
+    addx -3
+    addx 8
+    addx 1
+    addx 5
+    noop
+    noop
+    noop
+    noop
+    noop
+    addx -36
+    noop
+    addx 1
+    addx 7
+    noop
+    noop
+    noop
+    addx 2
+    addx 6
+    noop
+    noop
+    noop
+    noop
+    noop
+    addx 1
+    noop
+    noop
+    addx 7
+    addx 1
+    noop
+    addx -13
+    addx 13
+    addx 7
+    noop
+    addx 1
+    addx -33
+    noop
+    noop
+    noop
+    addx 2
+    noop
+    noop
+    noop
+    addx 8
+    noop
+    addx -1
+    addx 2
+    addx 1
+    noop
+    addx 17
+    addx -9
+    addx 1
+    addx 1
+    addx -3
+    addx 11
+    noop
+    noop
+    addx 1
+    noop
+    addx 1
+    noop
+    noop
+    addx -13
+    addx -19
+    addx 1
+    addx 3
+    addx 26
+    addx -30
+    addx 12
+    addx -1
+    addx 3
+    addx 1
+    noop
+    noop
+    noop
+    addx -9
+    addx 18
+    addx 1
+    addx 2
+    noop
+    noop
+    addx 9
+    noop
+    noop
+    noop
+    addx -1
+    addx 2
+    addx -37
+    addx 1
+    addx 3
+    noop
+    addx 15
+    addx -21
+    addx 22
+    addx -6
+    addx 1
+    noop
+    addx 2
+    addx 1
+    noop
+    addx -10
+    noop
+    noop
+    addx 20
+    addx 1
+    addx 2
+    addx 2
+    addx -6
+    addx -11
+    noop
+    noop
+    noop
+  )
+
+  test "10: Cathode-Ray Tube, part 1" do
+    expected = 13140
+
+    result = @input |> parse!() |> solve()
+
+    assert result == expected
+  end
+
+  @tag :skip
+  test "10: Cathode-Ray Tube, part 2" do
+    expected = :something
+
+    result = @input |> parse!() |> solve_again()
+
+    assert result == expected
+  end
+end