Day 10

Section

input = """
noop
addx 3
addx -5
"""

Part 1

input
|> String.split("\n", trim: true)
|> Stream.concat(["noop"])
|> Stream.transform({1, 1}, fn instruction, {cycle, x} = cur ->
  case instruction do
    "noop" -> {[cur], {cycle + 1, x}}
    "addx " <> n -> {[cur, {cycle + 1, x}], {cycle + 2, x + String.to_integer(n)}}
  end
end)
|> Stream.take_while(fn {cycle, _x} -> cycle <= 220 end)
# |> Stream.filter(fn {cycle, _x} -> cycle >= 180 && cycle <= 225 end)
|> Stream.filter(fn {cycle, _x} -> cycle in [20, 60, 100, 140, 180, 220] end)
|> Stream.map(fn {cycle, x} -> cycle * x end)
|> Enum.sum()

# |> Enum.to_list()

Part 2

input
|> String.split("\n", trim: true)
|> Stream.concat(["noop"])
|> Stream.transform({1, 1}, fn instruction, {cycle, x} = cur ->
  case instruction do
    "noop" -> {[cur], {cycle + 1, x}}
    "addx " <> n -> {[cur, {cycle + 1, x}], {cycle + 2, x + String.to_integer(n)}}
  end
end)
|> Stream.take_while(fn {cycle, _x} -> cycle <= 240 end)
|> Stream.map(fn {cycle, x} ->
  pixel = rem(cycle - 1, 40)
  newline? = if pixel == 39, do: "\n", else: ""

  if abs(x - pixel) <= 1 do
    "#"
  else
    "."
  end <> newline?
end)
|> Enum.join()
|> IO.puts()