AOC 2022 11

1.exs

System.argv()
|> List.first()
|> File.stream!()
|> Enum.reduce({1, 1, 0}, fn instruction, {x, cycle, total_strength} -> 
  {new_x, new_cycle} = 
    case instruction do
      "noop" <> _ ->
        {x, cycle + 1}
        
      "addx " <> val ->
        [neg, amt] = 
          ~r/(\-)?(\d{1,2}).*/
          |> Regex.run(val, capture: :all_but_first)
          
        amt = String.to_integer(amt)
          
        {x + (if neg == "-", do: amt |> Kernel.*(-1), else: amt), cycle + 2}
    end
    
  new_total_strength = 
    [20, 60, 100, 140, 180, 220]
    |> Enum.find(fn counted_cycle -> cycle <= counted_cycle && new_cycle > counted_cycle end)
    |> case do
      nil -> total_strength
      counted_cycle -> total_strength + counted_cycle * x
    end
  
  {new_x, new_cycle, new_total_strength}
end)
|> elem(2)
|> IO.inspect()

2.exs

crt_grid = 
  "."
  |> List.duplicate(40)
  |> List.duplicate(6)
  
divmod =
  fn e, d ->
	~w|div rem|a
	|> Enum.map(&apply(Kernel, &1, [e, d]))
	|> List.to_tuple()
  end

System.argv()
|> List.first()
|> File.stream!()
|> Enum.reduce({crt_grid, 1, 1}, fn instruction, {grid, x, cycle} -> 
	{new_x, new_cycle} = 
		case instruction do
  		"noop" <> _ ->
			{x, cycle + 1}
			
  		"addx " <> val ->
			[neg, amt] = 
	  		~r/(\-)?(\d{1,2}).*/
	  		|> Regex.run(val, capture: :all_but_first)
	  		
			amt = String.to_integer(amt)
	  		
			{x + (if neg == "-", do: amt |> Kernel.*(-1), else: amt), cycle + 2}
		end
	
	new_grid = 
		(cycle - 1)..(new_cycle - 2)
		|> Enum.reduce(grid, fn position, grid -> 
			{pixel_x, pixel_y} = divmod.(position, 40)
		
			if pixel_y in (x - 1)..(x + 1) do
				List.update_at(grid, pixel_x, & List.replace_at(&1, pixel_y, "#"))
			else
				grid
			end
		end)
	
	{new_grid, new_x, new_cycle}
end)
|> elem(0)
|> Enum.map(&Enum.join/1)
|> IO.inspect