From 8b542f4b14bc7c5bbe2b6df8f914da0f5d88f48c Mon Sep 17 00:00:00 2001
From: scarf <greenscarf005@gmail.com>
Date: Mon, 26 Aug 2024 01:50:02 +0900
Subject: [PATCH] feat: day 10

---
 2015/Day10.scala      | 23 +++++++++++++++++++++++
 2015/Day10.test.scala |  8 ++++++++
 2 files changed, 31 insertions(+)
 create mode 100644 2015/Day10.scala
 create mode 100644 2015/Day10.test.scala

diff --git a/2015/Day10.scala b/2015/Day10.scala
new file mode 100644
index 0000000..4b9d89b
--- /dev/null
+++ b/2015/Day10.scala
@@ -0,0 +1,23 @@
+package day10
+
+import scala.io.Source.fromFile
+
+val groupNums = raw"(.)\1*".r
+
+def nextNums(s: String) = groupNums
+  .findAllIn(s)
+  .map { xs => s"${xs.length}${xs.head}" }
+  .mkString
+
+def solution(input: String)(n: Int) =
+  (1 to n).foldLeft(input) { (acc, _) => nextNums(acc) }.length
+
+@main def main() =
+  val input = fromFile(".cache/10.txt").mkString.trim
+  val solver = solution(input)
+
+  val part1 = solver(40)
+  println(part1)
+
+  val part2 = solver(50)
+  println(part2)
diff --git a/2015/Day10.test.scala b/2015/Day10.test.scala
new file mode 100644
index 0000000..1e2126b
--- /dev/null
+++ b/2015/Day10.test.scala
@@ -0,0 +1,8 @@
+import munit.FunSuite
+import day10.*
+
+class Day10Tests extends FunSuite:
+  test("Part 1"):
+    Seq("1", "11", "21", "1211", "111221", "312211")
+      .sliding(2)
+      .map { case Seq(a, b) => assertEquals(nextNums(a), b) }