solve 2015 day 17

2015/README.md

@@ -16,7 +16,7 @@
 | :--: | :--: | :-:  | :-: | :-:  | :-:  | :-:  |
 |      |      | [1]  | [2] | [3]  | [4]  | [5]  |
 |  [6] | [7]  | [8]  | [9] | [10] | [11] | [12] |
-| [13] | [14] | [15] | [16]| 17   | 18   | 19   |
+| [13] | [14] | [15] | [16]| [17] | 18   | 19   |
 |  20  | 21   | 22   | 23  | 24   | 25   |      |
 
 [1]: ./lib/2015/1.ex
@@ -35,3 +35,4 @@
 [14]: ./lib/2015/14.ex
 [15]: ./lib/2015/15.ex
 [16]: ./lib/2015/16.ex
+[17]: ./lib/2015/17.ex

2015/lib/2015/17.ex

@@ -0,0 +1,36 @@
+import AOC
+
+aoc 2015, 17 do
+  def input() do
+    input_stream()
+    |> Stream.map(&String.to_integer/1)
+    |> Enum.sort(:desc)
+  end
+
+  def p1 do
+    input()
+    |> combinations()
+    |> Enum.filter(fn comb -> Enum.sum(comb) == 150 end)
+    |> length()
+  end
+
+  def p2 do
+    working_combinations =
+      input()
+      |> combinations()
+      |> Enum.filter(fn comb -> Enum.sum(comb) == 150 end)
+      |> Enum.sort_by(&length/1)
+
+    size_of_fewest_container_combination = working_combinations |> hd() |> length()
+
+    working_combinations
+    |> Enum.count(&(length(&1) == size_of_fewest_container_combination))
+  end
+
+  def combinations(values, combination \\ [])
+  def combinations([], combination), do: [combination]
+
+  def combinations([x | xs], combination) do
+    combinations(xs, [x | combination]) ++ combinations(xs, combination)
+  end
+end

2015/mix.exs

@@ -26,7 +26,8 @@ defmodule AdventOfCode2015.MixProject do
       {:jason, "~> 1.2"},
       {:libgraph, "~> 0.13.3"},
       {:nimble_parsec, "~> 1.0"},
-      {:nx, "~> 0.1.0-dev", github: "elixir-nx/nx", sparse: "nx", override: true}
+      {:nx, "~> 0.1.0-dev", github: "elixir-nx/nx", sparse: "nx", override: true},
+      {:rexbug, ">= 1.0.0"}
     ]
   end
 end

2015/mix.lock

@@ -6,5 +6,7 @@
   "libgraph": {:hex, :libgraph, "0.13.3", "20732b7bafb933dcf7351c479e03076ebd14a85fd3202c67a1c197f4f7c2466b", [:mix], [], "hexpm", "78f2576eef615440b46f10060b1de1c86640441422832052686df53dc3c148c6"},
   "nimble_parsec": {:hex, :nimble_parsec, "1.2.0", "b44d75e2a6542dcb6acf5d71c32c74ca88960421b6874777f79153bbbbd7dccc", [:mix], [], "hexpm", "52b2871a7515a5ac49b00f214e4165a40724cf99798d8e4a65e4fd64ebd002c1"},
   "nx": {:git, "https://github.com/elixir-nx/nx.git", "e23a678bf0ebcbbafe03f1b5ed78623f052ad486", [sparse: "nx"]},
+  "redbug": {:hex, :redbug, "1.2.2", "366d8961770ddc7bb5d209fbadddfa7271005487f938c087a0e385a57abfee33", [:rebar3], [], "hexpm", "b5fe7b94e487be559cb0ec1c0e938c9761205d3e91a96bf263bdf1beaebea729"},
+  "rexbug": {:hex, :rexbug, "1.0.5", "e4fce59d1cb4f574b2d84181507b4782bc4b6afcb64e2cd276003c563ffef766", [:mix], [{:mix_test_watch, ">= 0.5.0", [hex: :mix_test_watch, repo: "hexpm", optional: true]}, {:redbug, "~> 1.2", [hex: :redbug, repo: "hexpm", optional: false]}], "hexpm", "13a3f180a9e490686a774725a07a21caf05735b7c012824d86960e9541aab46a"},
   "xla": {:hex, :xla, "0.2.0", "689887888afb22587168d461f0e9ff83d7b06040273ea7082dbf9ff7eca33dcc", [:make, :mix], [{:elixir_make, "~> 0.4", [hex: :elixir_make, repo: "hexpm", optional: false]}], "hexpm", "a2e7b81413db49a159eabfb12dbd784a7c04b5c68c7b4057238d5ec9b110f2ec"},
 }