AdventOfCode/2020/elixir/day3/day3part2.exs

34 lines
631 B
Elixir

defmodule Day3Part2 do
def run do
answer =
slope(1, 1) *
slope(3, 1) *
slope(5, 1) *
slope(7, 1) *
slope(1, 2)
IO.puts(answer)
end
def slope(v_x, v_y) do
{_, trees} =
File.read!("input")
|> String.trim()
|> String.split("\n")
|> Enum.take_every(v_y)
|> Enum.map(&String.to_charlist/1)
|> Enum.reduce({0, 0}, fn row, {x, trees} ->
trees =
case Stream.cycle(row) |> Enum.at(x) do
?# -> trees + 1
?. -> trees
end
{x + v_x, trees}
end)
trees
end
end
Day3Part2.run()