From 414ae1f4fbbe7dfe1f9d10f4da2145b88d0cd59d Mon Sep 17 00:00:00 2001
From: Justin Wernick <j.wernick@eyeo.com>
Date: Wed, 11 Sep 2024 11:09:39 +0200
Subject: Day 5

---
 2015/day5.exs        | 33 +++++++++++++++++++++++++++++++++
 2015/inputs/.gitkeep |  0
 2 files changed, 33 insertions(+)
 create mode 100644 2015/day5.exs
 create mode 100644 2015/inputs/.gitkeep

diff --git a/2015/day5.exs b/2015/day5.exs
new file mode 100644
index 0000000..4e253c8
--- /dev/null
+++ b/2015/day5.exs
@@ -0,0 +1,33 @@
+santasList = File.stream!("inputs/day5.txt", [], :line)
+
+niceVowelRegex = ~r/[aeiou].*[aeiou].*[aeiou]/
+niceDuplicateRegex = ~r/(.)\1/
+naughtySubstrRegex = ~r/(ab)|(cd)|(pq)|(xy)/
+
+isNice1 = fn name ->
+  niceVowels? = Regex.match?(niceVowelRegex, name)
+  niceDuplicate? = Regex.match?(niceDuplicateRegex, name)
+  naughtySustr? = Regex.match?(naughtySubstrRegex, name)
+  niceVowels? && niceDuplicate? && !naughtySustr?
+end
+
+niceCount1 =
+  Enum.filter(santasList, isNice1)
+  |> Enum.count()
+
+IO.puts("Nice count 1: #{niceCount1}")
+
+niceDuplicatePairRegex = ~r/(..).*\1/
+niceLetterRepeatRegex = ~r/(.).\1/
+
+isNice2 = fn name ->
+  niceDuplicatePair? = Regex.match?(niceDuplicatePairRegex, name)
+  niceLetterRepeat? = Regex.match?(niceLetterRepeatRegex, name)
+  niceDuplicatePair? && niceLetterRepeat?
+end
+
+niceCount2 =
+  Enum.filter(santasList, isNice2)
+  |> Enum.count()
+
+IO.puts("Nice count 2: #{niceCount2}")
diff --git a/2015/inputs/.gitkeep b/2015/inputs/.gitkeep
new file mode 100644
index 0000000..e69de29
-- 
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