solve: day 1

2021/lib/advent_of_code/day01.ex

@@ -2,6 +2,12 @@ defmodule AdventOfCode.Day01 do
   @moduledoc """
   Day 1
   """
+
+  def parse_input_stream(input_stream) do
+    input_stream
+    |> Stream.map(&String.trim/1)
+    |> Stream.map(&String.to_integer/1)
+  end
 end
 
 defmodule AdventOfCode.Day01.Part1 do
@@ -15,9 +21,23 @@ defmodule AdventOfCode.Day01.Part1 do
   import AdventOfCode.Day01, warn: false
 
   @impl PuzzleSolver
-  def solve(_input_stream) do
-    :ok |> to_string()
+  def solve(input_stream) do
+    depth_stream =
+      input_stream
+      |> parse_input_stream()
+      |> Enum.to_list()
+
+    Enum.zip_with(
+      depth_stream,
+      Enum.drop(depth_stream, 1),
+      &</2
+    )
+    |> Stream.filter(&is_true?/1)
+    |> Enum.count()
   end
+
+  defp is_true?(true), do: true
+  defp is_true?(_), do: false
 end
 
 defmodule AdventOfCode.Day01.Part2 do
@@ -31,7 +51,18 @@ defmodule AdventOfCode.Day01.Part2 do
   import AdventOfCode.Day01, warn: false
 
   @impl PuzzleSolver
-  def solve(_input_stream) do
-    :ok |> to_string()
+  def solve(input_stream) do
+    parse_input_stream(input_stream)
+    |> Enum.to_list()
+    |> window_increases()
   end
-end
+
+  defp window_increases(list, acc \\ 0)
+
+  defp window_increases([a, b, c, d | _] = list, acc) do
+    acc = if a + b + c < b + c + d, do: acc + 1, else: acc
+    window_increases(Enum.drop(list, 1), acc)
+  end
+
+  defp window_increases(_, acc), do: acc
+end

2021/lib/advent_of_code/puzzle_solver.ex

@@ -6,7 +6,7 @@ defmodule AdventOfCode.PuzzleSolver do
   @doc """
   Given the input as a stream, return the solution as a string
   """
-  @callback solve(Enumerable.t()) :: String.t()
+  @callback solve(Enumerable.t()) :: any()
 
   def solve(mod, stream), do: apply(mod, :solve, [stream])
 

2021/mix.exs

@@ -26,6 +26,7 @@ defmodule AdventOfCode.MixProject do
   defp deps do
     [
       {:finch, "~> 0.9.0"},
+      {:mix_test_interactive, "~> 1.0", only: :dev, runtime: false},
       {:progress_bar, "~> 2.0"}
     ]
   end

2021/mix.lock

@@ -1,10 +1,13 @@
 %{
   "castore": {:hex, :castore, "0.1.13", "ccf3ab251ffaebc4319f41d788ce59a6ab3f42b6c27e598ad838ffecee0b04f9", [:mix], [], "hexpm", "a14a7eecfec7e20385493dbb92b0d12c5d77ecfd6307de10102d58c94e8c49c0"},
   "decimal": {:hex, :decimal, "2.0.0", "a78296e617b0f5dd4c6caf57c714431347912ffb1d0842e998e9792b5642d697", [:mix], [], "hexpm", "34666e9c55dea81013e77d9d87370fe6cb6291d1ef32f46a1600230b1d44f577"},
+  "file_system": {:hex, :file_system, "0.2.10", "fb082005a9cd1711c05b5248710f8826b02d7d1784e7c3451f9c1231d4fc162d", [:mix], [], "hexpm", "41195edbfb562a593726eda3b3e8b103a309b733ad25f3d642ba49696bf715dc"},
   "finch": {:hex, :finch, "0.9.0", "8b772324aebafcaba763f1dffaa3e7f52f8c4e52485f50f48bbb2f42219a2e87", [:mix], [{:castore, "~> 0.1", [hex: :castore, repo: "hexpm", optional: false]}, {:mint, "~> 1.3", [hex: :mint, repo: "hexpm", optional: false]}, {:nimble_options, "~> 0.3.5", [hex: :nimble_options, repo: "hexpm", optional: false]}, {:nimble_pool, "~> 0.2", [hex: :nimble_pool, repo: "hexpm", optional: false]}, {:telemetry, "~> 0.4 or ~> 1.0", [hex: :telemetry, repo: "hexpm", optional: false]}], "hexpm", "a93bfcad9ca50fa3cb2d459f27667d9a87cfbb7fecf9b29b2e78a50bc2ab445d"},
   "mint": {:hex, :mint, "1.4.0", "cd7d2451b201fc8e4a8fd86257fb3878d9e3752899eb67b0c5b25b180bde1212", [:mix], [{:castore, "~> 0.1.0", [hex: :castore, repo: "hexpm", optional: true]}], "hexpm", "10a99e144b815cbf8522dccbc8199d15802440fc7a64d67b6853adb6fa170217"},
+  "mix_test_interactive": {:hex, :mix_test_interactive, "1.1.0", "e3e048ea8b56637c8e5614044483e11d78f81f70e9afb811c06ad3db69704c32", [:mix], [{:file_system, "~> 0.2", [hex: :file_system, repo: "hexpm", optional: false]}, {:typed_struct, "~> 0.2.1", [hex: :typed_struct, repo: "hexpm", optional: false]}], "hexpm", "2288a2edc735ca4879a7c17b9fd9fd4b8b84a57a775c3228db4655806a0a4799"},
   "nimble_options": {:hex, :nimble_options, "0.3.7", "1e52dd7673d36138b1a5dede183b5d86dff175dc46d104a8e98e396b85b04670", [:mix], [], "hexpm", "2086907e6665c6b6579be54ef5001928df5231f355f71ed258f80a55e9f63633"},
   "nimble_pool": {:hex, :nimble_pool, "0.2.4", "1db8e9f8a53d967d595e0b32a17030cdb6c0dc4a451b8ac787bf601d3f7704c3", [:mix], [], "hexpm", "367e8071e137b787764e6a9992ccb57b276dc2282535f767a07d881951ebeac6"},
   "progress_bar": {:hex, :progress_bar, "2.0.1", "7b40200112ae533d5adceb80ff75fbe66dc753bca5f6c55c073bfc122d71896d", [:mix], [{:decimal, "~> 2.0", [hex: :decimal, repo: "hexpm", optional: false]}], "hexpm", "2519eb58a2f149a3a094e729378256d8cb6d96a259ec94841bd69fdc71f18f87"},
   "telemetry": {:hex, :telemetry, "1.0.0", "0f453a102cdf13d506b7c0ab158324c337c41f1cc7548f0bc0e130bbf0ae9452", [:rebar3], [], "hexpm", "73bc09fa59b4a0284efb4624335583c528e07ec9ae76aca96ea0673850aec57a"},
+  "typed_struct": {:hex, :typed_struct, "0.2.1", "e1993414c371f09ff25231393b6430bd89d780e2a499ae3b2d2b00852f593d97", [:mix], [], "hexpm", "8f5218c35ec38262f627b2c522542f1eae41f625f92649c0af701a6fab2e11b3"},
 }

2021/test/advent_of_code/day01/part_1_test.exs

@@ -3,9 +3,18 @@ defmodule AdventOfCode.Day01.Part1Test do
 
   test "returns :ok" do
     input = ~S"""
-    input
+    199
+    200
+    208
+    210
+    200
+    207
+    240
+    269
+    260
+    263
     """
 
-    assert_solution(input, "ok")
+    assert_solution(input, 7)
   end
-end
+end

2021/test/advent_of_code/day01/part_2_test.exs

@@ -3,9 +3,19 @@ defmodule AdventOfCode.Day01.Part2Test do
 
   test "returns :ok" do
     input = ~S"""
-    input
+    199
+    200
+    208
+    210
+    200
+    207
+    240
+    269
+    260
+    263
     """
 
-    assert_solution(input, "ok")
+    assert_solution(input, 5)
   end
-end
+end
+