From 29c49417f89169c03ca05724da3c88880d3a1a17 Mon Sep 17 00:00:00 2001
From: Tomasz Chojnacki <tomaszchojnacki2001@gmail.com>
Date: Fri, 27 Jan 2023 15:00:57 +0100
Subject: Solve first two days of 2019 in Elixir

---
 aoc-2019-elixir/lib/day01.ex | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)
 create mode 100644 aoc-2019-elixir/lib/day01.ex

(limited to 'aoc-2019-elixir/lib/day01.ex')

diff --git a/aoc-2019-elixir/lib/day01.ex b/aoc-2019-elixir/lib/day01.ex
new file mode 100644
index 0000000..6545f19
--- /dev/null
+++ b/aoc-2019-elixir/lib/day01.ex
@@ -0,0 +1,32 @@
+defmodule Day01 do
+  @spec part1([integer]) :: integer
+  def part1(input) do
+    input
+    |> Enum.map(&naive_fuel_requirement/1)
+    |> Enum.sum()
+  end
+
+  @spec part2([integer]) :: integer
+  def part2(input) do
+    input
+    |> Enum.map(&recursive_fuel_requirement/1)
+    |> Enum.sum()
+  end
+
+  defp naive_fuel_requirement(mass) do
+    div(mass, 3) - 2
+  end
+
+  defp recursive_fuel_requirement(mass) do
+    fuel_mass = div(mass, 3) - 2
+
+    case fuel_mass do
+      n when n <= 0 -> 0
+      _ -> fuel_mass + recursive_fuel_requirement(fuel_mass)
+    end
+  end
+end
+
+input = Util.Input.read_numbers("day01")
+input |> Day01.part1() |> IO.inspect()
+input |> Day01.part2() |> IO.inspect()
-- 
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