From 6997fbea377ca44c445e112d594eb077dcc8a76a Mon Sep 17 00:00:00 2001
From: Justin Wernick <j.wernick@eyeo.com>
Date: Fri, 27 Sep 2024 11:43:21 +0200
Subject: Day 14

---
 2015/day14.exs | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 48 insertions(+)
 create mode 100644 2015/day14.exs

(limited to '2015/day14.exs')

diff --git a/2015/day14.exs b/2015/day14.exs
new file mode 100644
index 0000000..0728486
--- /dev/null
+++ b/2015/day14.exs
@@ -0,0 +1,48 @@
+reindeer =
+  File.stream!("inputs/day14.txt")
+  |> Enum.map(fn line ->
+    [speed, stamina, recovery] =
+      Regex.run(
+        ~r/\w+ can fly (\d+) km\/s for (\d+) seconds, but then must rest for (\d+) seconds./,
+        line
+      )
+      |> Stream.drop(1)
+      |> Stream.map(&Integer.parse/1)
+      |> Enum.map(fn {i, _} -> i end)
+
+    {speed, stamina, recovery}
+  end)
+
+totalRaceLength = 2503
+
+distancesAfterRaceLength = fn raceLength ->
+  Enum.map(reindeer, fn {speed, stamina, recovery} ->
+    fullIterationDuration = stamina + recovery
+    fullIterationCount = div(raceLength, fullIterationDuration)
+    lastIterationDuration = rem(raceLength, fullIterationDuration)
+    lastIterationRuntime = min(stamina, lastIterationDuration)
+
+    runtime = fullIterationCount * stamina + lastIterationRuntime
+    runtime * speed
+  end)
+end
+
+maxDistance = distancesAfterRaceLength.(totalRaceLength) |> Enum.max()
+IO.puts("Max distance: #{maxDistance}")
+
+maxPoints =
+  Enum.map(1..totalRaceLength, fn raceLength ->
+    distances = distancesAfterRaceLength.(raceLength)
+    maxDistance = Enum.max(distances)
+
+    Enum.map(distances, fn
+      ^maxDistance -> 1
+      _ -> 0
+    end)
+  end)
+  |> List.zip()
+  |> Enum.map(&Tuple.to_list/1)
+  |> Enum.map(&Enum.sum/1)
+  |> Enum.max()
+
+IO.puts("Max points: #{maxPoints}")
-- 
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