From bfce436b111fd8d45ae5b9f61dd8d05323867891 Mon Sep 17 00:00:00 2001
From: Santo Cariotti <santo@dcariotti.me>
Date: Fri, 13 Dec 2024 16:47:51 +0100
Subject: Add day1 for 2024

---
 2024/scala/.gitignore |  2 ++
 2024/scala/day1.scala | 38 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 40 insertions(+)
 create mode 100644 2024/scala/.gitignore
 create mode 100644 2024/scala/day1.scala

diff --git a/2024/scala/.gitignore b/2024/scala/.gitignore
new file mode 100644
index 0000000..b3c6c86
--- /dev/null
+++ b/2024/scala/.gitignore
@@ -0,0 +1,2 @@
+.bsp/
+.scala-build/
diff --git a/2024/scala/day1.scala b/2024/scala/day1.scala
new file mode 100644
index 0000000..3803572
--- /dev/null
+++ b/2024/scala/day1.scala
@@ -0,0 +1,38 @@
+import scala.io.Source
+
+object Day1 {
+  def part1(lefts: Array[Int], rights: Array[Int]): Int = {
+    lefts
+      .zip(rights)
+      .map { case (l, r) =>
+        math.abs(l - r)
+      }
+      .sum
+  }
+
+  def part2(lefts: Array[Int], rights: Array[Int]): Int = {
+    val rightsCount = rights.groupBy(identity).map { case (k, v) =>
+      (k, v.size)
+    }
+    lefts
+      .map(x => x * rightsCount.getOrElse(x, 0))
+      .sum
+  }
+
+  def main(args: Array[String]): Unit = {
+    val lines =
+      Source
+        .fromFile(args(0))
+        .mkString
+        .split("\n")
+        .map(_.split("   ").map(_.toInt))
+
+    val (lefts_, rights_) = lines.map(arr => (arr(0), arr(1))).unzip
+    val lefts = lefts_.sorted
+    val rights = rights_.sorted
+
+    assert(part1(lefts, rights) == 3569916)
+    assert(part2(lefts, rights) == 26407426)
+  }
+}
+
-- 
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