day5

Author: akdemironur

.gitignore

@@ -8,3 +8,4 @@ erl_crash.dump
 *.beam
 /config/*.secret.exs
 .elixir_ls/
+input

05/sample_input

@@ -0,0 +1,33 @@
+seeds: 79 14 55 13
+
+seed-to-soil map:
+50 98 2
+52 50 48
+
+soil-to-fertilizer map:
+0 15 37
+37 52 2
+39 0 15
+
+fertilizer-to-water map:
+49 53 8
+0 11 42
+42 0 7
+57 7 4
+
+water-to-light map:
+88 18 7
+18 25 70
+
+light-to-temperature map:
+45 77 23
+81 45 19
+68 64 13
+
+temperature-to-humidity map:
+0 69 1
+1 0 69
+
+humidity-to-location map:
+60 56 37
+56 93 4

05/sol.exs

@@ -0,0 +1,98 @@
+defmodule Day05 do
+  defp read_input(file_path) do
+    case File.read(file_path) do
+      {:ok, content} ->
+        sections = content |> String.split("\n\n", trim: true)
+
+        seeds =
+          sections
+          |> Enum.at(0)
+          |> String.split(" ", trim: true)
+          |> tl
+          |> Enum.map(&String.to_integer/1)
+
+        maps = 1..7 |> Enum.map(&read_section_n(&1, sections))
+        {seeds, maps}
+
+      {:error, reason} ->
+        raise "Oh no! #{reason}"
+    end
+  end
+
+  defp read_section_n(n, sections) do
+    sections
+    |> Enum.at(n)
+    |> String.split("\n", trim: true)
+    |> Enum.slice(1..-1)
+    |> Enum.map(&String.split(&1, " ", trim: true))
+    |> Enum.map(fn x -> Enum.map(x, &String.to_integer/1) end)
+    |> Enum.sort_by(&Enum.at(&1, 1))
+  end
+
+  defp lookupRange([dst, src, sz], x) do
+    if x >= src and x < src + sz do
+      dst + (x - src)
+    else
+      nil
+    end
+  end
+
+  defp lookupSectionH(section, [start, sz], acc) do
+    droppedSection = Enum.drop_while(section, fn [_, src, sz] -> src + sz <= start end)
+
+    case droppedSection do
+      [] ->
+        [[start, sz] | acc]
+
+      [[dst, src, sz2] | _] ->
+        if src > start do
+          if src - start > sz do
+            [[start, sz] | acc]
+          else
+            lookupSectionH(section, [src, sz - src + start], [[start, src - start] | acc])
+          end
+        else
+          if src + sz2 > start + sz do
+            [[dst + start - src, sz] | acc]
+          else
+            lookupSectionH(section, [src + sz2, sz - (sz2 - start + src)], [
+              [dst + start - src, sz2 - start + src] | acc
+            ])
+          end
+        end
+    end
+  end
+
+  defp lookupSection(section, x) when is_integer(x) do
+    lu =
+      section
+      |> Enum.map(&lookupRange(&1, x))
+      |> Enum.filter(fn x -> x != nil end)
+
+    case lu do
+      [] -> x
+      [a] -> a
+    end
+  end
+
+  defp lookupSection(section, x) do
+    x |> Enum.map(&lookupSectionH(section, &1, [])) |> Enum.concat()
+  end
+
+  defp lookupMap(map, x) do
+    map |> Enum.reduce(x, &lookupSection(&1, &2))
+  end
+
+  def partA(file_path) do
+    {seeds, maps} = read_input(file_path)
+    seeds |> Enum.map(&lookupMap(maps, &1)) |> Enum.min()
+  end
+
+  def partB(file_path) do
+    {seedRanges, maps} = read_input(file_path)
+    lookupMap(maps, Enum.chunk_every(seedRanges, 2)) |> Enum.min_by(fn [x, _] -> x end) |> hd
+  end
+end
+
+IO.puts(Day05.partA("./input"))
+IO.puts(Day05.partB("./input"))