Day 4 Part 1

2020/day4/day4.ex

@@ -0,0 +1,46 @@
+defmodule Day4 do
+  defp read_input do
+    Path.expand('input', Path.dirname(__ENV__.file))
+    |> File.read!()
+  end
+
+  defp parse_passports(text) do
+    String.split(text, "\n\n")
+    |> Enum.map(fn block ->
+      fields = String.split(block)
+
+      Enum.reduce(fields, %{}, fn field, passport ->
+        [key, val] = String.split(field, ":")
+        Map.put(passport, key, val)
+      end)
+    end)
+  end
+
+  @required_fields [
+    "byr",
+    "iyr",
+    "eyr",
+    "hgt",
+    "hcl",
+    "ecl",
+    "pid"
+    # "cid"
+  ]
+
+  defp valid?(passport) do
+    Enum.all?(@required_fields, fn field ->
+      case Map.fetch(passport, field) do
+        {:ok, _val} -> true
+        :error -> false
+      end
+    end)
+  end
+
+  def part1 do
+    read_input()
+    |> parse_passports()
+    |> Enum.count(&valid?/1)
+  end
+end
+
+Day4.part1() |> IO.inspect()