Day 6

lib/day6/day6.ex

@@ -0,0 +1,61 @@
+defmodule Day6 do
+  @example """
+  abc
+
+  a
+  b
+  c
+
+  ab
+  ac
+
+  a
+  a
+  a
+  a
+
+  b
+  """
+
+  def part1(example \\ false) do
+    parse_input(example)
+    |> Enum.map(&questions_with_any_yes/1)
+    |> Enum.map(&MapSet.size/1)
+    |> Enum.sum()
+  end
+
+  def part2(example \\ false) do
+    parse_input(example)
+    |> Enum.map(&questions_with_all_yes/1)
+    |> Enum.map(&MapSet.size/1)
+    |> Enum.sum()
+  end
+
+  def parse_input(example) do
+    if(example, do: @example, else: File.read!("lib/day6/input.txt"))
+    |> String.trim()
+    |> String.split("\n\n")
+  end
+
+  def questions_with_any_yes(str) do
+    str
+    |> String.replace(~r/\s/, "")
+    |> String.to_charlist()
+    |> MapSet.new()
+  end
+
+  def questions_with_all_yes(str) do
+    people =
+      str
+      |> String.split("\n")
+      |> Enum.map(fn person ->
+        person
+        |> String.to_charlist()
+        |> MapSet.new()
+      end)
+
+    people
+    |> Enum.drop(1)
+    |> Enum.reduce(List.first(people), &MapSet.intersection/2)
+  end
+end