Day 4: Ceres Search

Mix.install([:kino])

Section

input = Kino.Input.textarea("input")

input = Kino.Input.read(input)

Part 1

splitted = String.split(input, "\n", trim: true)
cols = String.length(hd(splitted))
rows = length(splitted)

get_pos = fn(pos_map, x, y) ->
  pos_map["#{x}:#{y}"]
end

pos_map = for x <- 1..cols, y <- 1..rows, into: %{} do
  {"#{x}:#{y}", String.at(Enum.at(splitted, y-1), x-1)}
end

for x <- 1..cols, y <- 1..rows, pos_map["#{x}:#{y}"] == "X" do
  for xd <- [-1, 0, 1], yd <- [-1, 0, 1], 
    !(xd == 0 &amp;&amp; yd == 0), 
    !(y + 1 * yd > rows), 
    !(x + 1 * xd > cols), 
    !(x + 1 * xd < 1),
    !(y + 1 * yd < 1)
  do
    if "X#{get_pos.(pos_map, x + 1 * xd, y + 1 * yd)}#{get_pos.(pos_map, x + 2 * xd, y + 2 * yd)}#{get_pos.(pos_map, x + 3 * xd, y + 3 * yd)}" == "XMAS" do
      1
    else
      0
    end
  end
end
|> List.flatten()
|> Enum.sum()

Part 2

splitted = String.split(input, "\n", trim: true)
cols = String.length(hd(splitted))
rows = length(splitted)

get_pos = fn(pos_map, x, y) ->
  pos_map["#{x}:#{y}"]
end

pos_map = for x <- 1..cols, y <- 1..rows, into: %{} do
  {"#{x}:#{y}", String.at(Enum.at(splitted, y-1), x-1)}
end

for x <- 1..cols, y <- 1..rows, pos_map["#{x}:#{y}"] == "A" do
  phr1 = "#{get_pos.(pos_map, x + 1 * -1, y + 1 * 1)}#{get_pos.(pos_map, x + 1 * 1, y + 1 * -1)}" |>String.split("", trim: true) |> Enum.sort() |> List.to_string()  
  phr2 = "#{get_pos.(pos_map, x + 1 * -1, y + 1 * -1)}#{get_pos.(pos_map, x + 1 * 1, y + 1 * 1)}" |>String.split("", trim: true) |> Enum.sort() |> List.to_string()
  if(phr1 == "MS" &amp;&amp; phr2 == "MS", do: 1, else: 0)
end
|> Enum.sum()

a = 1
b = 1
IO.inspect(1 == a)