Solve 2016/24

Author: code-shoily

lib/2016/day_24.ex

@@ -0,0 +1,77 @@
+defmodule AdventOfCode.Y2016.Day24 do
+  @moduledoc """
+  --- Day 24: Air Duct Spelunking ---
+  Problem Link: https://adventofcode.com/2016/day/24
+  Difficulty: m
+  Tags: graph shortest-path tsp grid matrix
+  """
+  alias AdventOfCode.Helpers.{InputReader, Transformers}
+  alias Yog.Builder.Grid
+  alias Yog.Pathfinding.Matrix
+
+  def input, do: InputReader.read_from_file(2016, 24)
+
+  def run(input \\ input()) do
+    # Build the graph and identify POIs (0-7).
+    {graph, pois} = parse(input)
+
+    # Pre-calculate distances between all POIs using the Matrix API.
+    # It intelligently selects Dijkstra or Floyd-Warshall.
+    poi_ids = Map.values(pois)
+    {:ok, dist_matrix} = Matrix.distance_matrix(graph, poi_ids)
+
+    # Simplified label-based distance map.
+    label_to_id = Map.new(pois, fn {label, id} -> {id, label} end)
+
+    distances =
+      Map.new(dist_matrix, fn {{u, v}, d} ->
+        {{label_to_id[u], label_to_id[v]}, d}
+      end)
+
+    max_poi = Map.keys(pois) |> Enum.max()
+    targets = Enum.to_list(1..max_poi)
+
+    {solve_tsp(targets, distances, false), solve_tsp(targets, distances, true)}
+  end
+
+  def parse(data \\ input()) do
+    # Grid builder creates an undirected graph and identifies walls.
+    grid_data = Transformers.lines(data) |> Enum.map(&String.graphemes/1)
+    grid = Grid.from_2d_list(grid_data, :undirected, Grid.avoiding("#"))
+    graph = Grid.to_graph(grid)
+
+    # Extract positions of numbered POIs.
+    pois =
+      Enum.reduce(graph.nodes, %{}, fn {id, data}, acc ->
+        case Integer.parse(data) do
+          {label, ""} -> Map.put(acc, label, id)
+          _ -> acc
+        end
+      end)
+
+    {graph, pois}
+  end
+
+  defp solve_tsp(targets, distances, return_to_start?) do
+    targets
+    |> permutations()
+    |> Enum.map(fn p ->
+      path = if return_to_start?, do: [0 | p] ++ [0], else: [0 | p]
+      calculate_path_dist(path, distances)
+    end)
+    |> Enum.min()
+  end
+
+  defp calculate_path_dist(path, distances) do
+    path
+    |> Enum.chunk_every(2, 1, :discard)
+    |> Enum.map(fn [a, b] -> distances[{a, b}] end)
+    |> Enum.sum()
+  end
+
+  defp permutations([]), do: [[]]
+
+  defp permutations(list) do
+    for x <- list, rest <- permutations(list -- [x]), do: [x | rest]
+  end
+end

priv/input_files/2016_24.txt

@@ -0,0 +1,41 @@
+#########################################################################################################################################################################################
+#.#.....#.........#.....#.......#.#...........#...#.....................#...................#.....#.......#.#...#...................#...#...........#...#...#...#...#...#...#.....#...#.#
+#.###.#.#.###.#.#.#.#.#.#########.#.#.###.#.#.#.###.#.#.#.#####.#.###.###.#.###.#.#.#.###.#.#.#.#.#.#.#.#.#.#.#.#.###.###.#.#.#.#.#.#.###.###.#.#.#.#.#.#.#####.#.#.#.#.#.#.#.#.#.#.#.#.#
+#.#...#.#...#...#...#.........#...#...#...#.............#.......#.....#.....#...#.#.......#.......#.........#.#.#...#...#...#.....#...#...#.#.#.#..3#.....#.........#.#...#.....#.#...#.#
+#.#.#.#.#.#.#.#.#.#.#.###.###.#.#####.#.#.#####.#.###.#####.#.###.#.###.#.###.#####.###.###.#.###.#.#.#.###.#####.###.###.###.#.###.#.#####.#.###.#.#.###.###.#.###.#.###.#.###.###.#.#.#
+#.....#.....#...#.....#...#.#.#.#...#...#...#.#...#...#.......#...#.....#...#.....#.......#.#...#.....#...#.#...#.....#.....#.#.#...#.#.......#.......#...#...#.#.#.#.#.#...#.......#.#.#
+#.###.#.###.#.###.#.#.#.#.#.#####.#.#.#.#####.#.#.#.#.#.#.#.###.#.#.###.#.#.#.###.###.###.#.###.#.#.#.###.#.#.###.#.#####.#.#.#.#.#.#.#.#####.#.#.#.###.#.#.#.###.#.#.#.###.#.#######.#.#
+#...#.#.#5#.#.........#.....#.....#.#.#.#...........#.#.....#.#...#.........#.....#...#.#...#.#.#.#...#.....#...#.#.....#...#...#.#.#...#.#.....#...#...#.....#.......#...#...#.....#...#
+#.#.#.###.#.#########.###.#.###.#.#.#.###.#.#######.#.#.#.#.#.#.#######.###.#.#.#.#.###.#.###.#.#.#.###.#.#####.###.###.###.#.#.#.#.#.#.#.###.#####.#######.#.#.#.###.#.#.###.#.###.###.#
+#...#.#.......#.#.......#.#...#...#.....#.#.#.....#.#...#...#...#.....#.....#.#...#.#.........#.....#...........#.......#.....#...#.#.....#.......#.#...#...#.#.......#.#.#.#.#.........#
+###.#.#.###.#.#.#.#.#.#.#.#.#.#.#######.#.#.#.#.###.#.#.###.#.#.#.#.#.#.#####.#####.#.#.#.###.#.#####.#.#.#.###.#.#.#.###.#.#.#.#.#.#.#.#.#.#.###.###.#.#.#.#.#.#.#.#.#####.###.#######.#
+#.#...#.#...#.#.....#...#...#...#.....#.........#.............#.......#.............#.........#.......#...#...#...#.......#.....#.......#...#.....#.....#.........#.#.#...#.#...#.....#6#
+#.#.#.#.###.#.#.###.#.#.#.#.#.###.#.#.#.#.#####.#.#.###.#.###.#.#.#######.#.#####.#.#######.#####.#######.#.###.#.#####.#.#.#.#.#.#####.#.#.#.#.#.#######.###.#.###.#.#.#.#.#.#.#.#.#.#.#
+#...#.#...#.#...........#...#.......#...#...#.......#...#.#.....#.#.................#...#...#.#.....#.....#.#.......#...#.....#...#.#...#.......#.#.#...#.......#...#.#.#.........#.....#
+#####.###.#.###.#####.###.#.#.#.#####.#.###.#.#.#####.#.#.#.#.#.###.#####.###.#.#####.###.#.#.#.#.#.###.###.#######.#.#.#.#.#.#.#.#.###.###.###.###.#.#.#.#.#####.#.#.###.#.#####.###.###
+#...#.#.........#.#...#.#...........#.#...#...#.#...#...#...#.......#...#...#...............................#.....#...#...#.....#...#.#.#.#...#.#.......#.....#.....#.#.#...#...#...#...#
+###.#.#.#########.#.###.#.#.###.#######.#.###.#.#.###.#.#.###.#####.###.#.#.#####.#.#.#.#.###.###.#.#.#.#.#.#.#######.#.#.#.###.###.#.#.#.#.#.###.###.###.###.#####.#.#.#.#.###.#.#.#.#.#
+#.#...#.#.#.#.......#...#.....#.#...#...#.....#.............#.#...#.#...#.#.......#.......#...................#.....#.#.....#.#...#.#...#.#...#...#...#...#.....#.#...#.........#...#...#
+#.#.#.###.#.#########.#.#.#.#.#.#.#.#.###.#.###.#.#.#.#.#######.#.#####.#####.#.#.###.###.#.#.#.###.#####.###.#.#.#.#.#.#.###.#####.#####.#.#.#####.#######.###.#.#.#.#.#.#####.###.#.#.#
+#...#.#.....#.#.#4#.#...#...#.........#.#.#...#...#.#.#.....#...#.#.....#.....#.......#...#.#.#.......#...#.#...#.....#.#.....#.........#.#...#.........#...#.#...#...............#.#...#
+#####.#.#.###.#.#.#.#.#.###.#.#.###.###.#.#.#.#.#.#.###.###.#.#.#.#.#######.###.###.#.###.#.#####.#.###.#.#.###.#####.#.#######.#.#######.###.#.#.###.#.#.###.#.#########.#.###.#.#.###.#
+#...#.....#.....#.......#.#...#.#.#.#.....#...#.#.#...........#.#.............#.#.......#.#.#...........#.............#.....#.#.......#...#.....#.#...#.#...#.#.........#.#...#.#...#...#
+#.#.#.###.#########.#.#.#.#.#.###.###.###.#######.#.#.###.#.#.#.#.###.#.#.#.#.###.#####.###.#####.#.###.#.#.###.#.#.#.#####.#.#.#.#.###.#.#.#.###.#.###.#.#.#.#.###.###.#.#.#######.#.###
+#...#.....#.#.......#...#.#...#.......#.......#...#.#...#...#.#.#...........#...#.......#...#.......#.#.....#.....#...#.......#...#.........#.....#.#.#.#.#...#.#.........#...........#.#
+#.#.###.#.#.#.#.#.#.#.#.#.#.#.#.###.#.#.#.#.#.#.#.###.###.###.#.#.#.#####.###.#.#.#########.#.#.###.#.#.#.###.###.#.#.###.#.#.#.#.###.#.#.#.#.#.#.#.#.#.#.#.###.#.###.#.#.#.#####.#.#.#.#
+#.#.....#.#...#.#.#.#.#...#.......#.#...#.#.#.#...#...#.......#.......#...#...#.#...#.....#.#...#...#...#.........#...#.#.#.....#.#.....#.....#.............#...#.......#...........#...#
+#.#.#.#.#.#.###.###.###.###.#.###.#.#.#.#.#.#.#.#.#.#######.#####.#.#.#####.#.#.###.#.#.#####.#.#####.#.#.#.#.#.#.###.#.###.#.###.#.#.###.###.#.#.#.#.#.###.#.#.#.###.###.#.#.#####.#####
+#...#.........#.....#.#.....#.....#.#...#.#...#...........#.#.......#.........#...............#.#...#...#.#...#.....#.#.#.....#...#.......#...#.....#...#...#.....#...#...#...#7#.......#
+#.#.#.###.#######.###.#.#####.#.###.#.###.#.#######.#.#.#.#.###.###.#.#.#####.#.#.#.###.#.#.###.#.#.#####.#.#.###.#.#.#.#.#.###.#.#.#.###.#.#.###.#####.#.###.#.###.#.###.#.#.#.#######.#
+#...#.#.............#.#...#0..#.#...........#.#.............#...#...#...#.......#.....#...#.......#...#.....#.....#.#.#.#...#.#.#.#...#...#...#.....#.#.#...........#.....#.....#.#.....#
+###.#.###.#.#.#.#.#.#.###.#.#.#.###.###.#####.#.#####.###.#.#.#.#.#####.#.#.#.#####.#####.#.#.#.#.#.#####.#.#.#.#.#.#.#.#.#.#.#.#.#.#####.#.###.#####.#.#.###.#######.#.#.#.#####.#.#.#.#
+#.#.....#...#.......#.....#.....#...#.....#...........#...#.....#.#.....#.......#.....#.....#.............#.#...#.....#.#.........#...#...#.#.............#...#...#...#.#...#.#.......#.#
+#.#.#.#.#.###.###.###.#.#.#.#######.#.#.#.#####.#.###.#.###.#.#.#.#.###.#.###.#.#.###.#.#.#.#########.#.#.#.###.#.#.###.#.#######.#.###.#.#.#.#.#.#.###.#.#.#.###.#.#.#.#####.#.#.###.###
+#.....#...#.......#.....#...#.#.....#...#.........#...#.....#.#...#.......#...............#.#.......#.......#.#...........#.....#.......#.#.#.#.#...#.......#.....#.....#...#.......#...#
+#.###.###.#.#######.#.#.#.#.#.#.#.#.###.#.#######.#.###.#.#####.###.#.###.###.#####.#.###.###.#.#.#.#####.#.#.#.#########.#.#.#.#####.#.#.#.###.#.###.#.###.#.###.###.#.#.#.#.#.#.#.#.#.#
+#.#.#.......#.#.#...#.....#.....#.#...#.....#...#.....#.#.#...........#...#...#...#.....#...#.......#.#.....#.........#...#.#...........#.#.#...#...#......1#.....#...#.#...#...#...#...#
+#.#.#.#.#####.#.#.###.#####.#####.#.#.###.###.#.#####.###.#.#.#.#.#####.###.###.#.#.###.###.#######.#.###.#.#.###.#.#.#.###.#.###########.#.#.###.#######.#######.#.###.###.#.#.#.###.#.#
+#...#.........#.....#...#.....#.....#...#.....#.......#.#...#...#.#.......#.....#...#.........#.....#...#.#.#...............#.............#.......#.........#.........#...........#.....#
+#.#.#.###.#.#.#.###.###.#.#####.#####.#.###.#.###.#.#.#.###.#.#####.#.###.#.#.#.#.#.#.#.###.###.###.###.#.#.#.#.#.#.#####.###.#.#.#######.#.#.#.###.#.###.#.#.#.###.#####.###.###.#.#.###
+#.........#.....#.......#....2#.........#.....#.....#.#.......#.#.#.......#.#...#...........#.#.#...#...#.#...#.....#.....#.#.#.#.#.......#...#.#.#.#.........#.#.........#.#...#...#.#.#
+#########################################################################################################################################################################################

test/2016/day_24_test.exs

@@ -0,0 +1,12 @@
+defmodule AdventOfCode.Y2016.Day24Test do
+  @moduledoc false
+
+  use ExUnit.Case, async: true
+  @moduletag :y1624
+
+  alias AdventOfCode.Y2016.Day24, as: Solution
+
+  test "Year 2016, Day 24 run/1" do
+    assert Solution.run() == {462, 676}
+  end
+end