Day 1 part 1

src/main/scala/Day01.scala

@@ -1,6 +1,26 @@
-import cats.derived.*
 import cats.syntax.all.*
 
 object Day01:
 
-  def day01: Int = 42
+  case class LocationId(value: Int)
+
+  object LocationId:
+    given Ordering[LocationId] = Ordering.by(_.value)
+
+  case class Input(left: List[LocationId], right: List[LocationId]):
+    def totalDistance: Long = left.sorted.zip(right.sorted).map((l, r) => Math.abs(l.value - r.value).toLong).sum
+
+  object Input:
+    def parse(inputs: List[String]): Option[Input] =
+      inputs.traverse {
+        _.split(" {3}") match
+          case Array(l, r) => (l.toIntOption, r.toIntOption).tupled
+          case _           => None
+      }.map { lrs =>
+        Input(
+          left = lrs.map((l, _) => LocationId(l)),
+          right = lrs.map((_, r) => LocationId(r))
+        )
+      }
+
+  def totalDistance(inputs: List[String]): Option[Long] = Input.parse(inputs).map(_.totalDistance)

src/test/scala/Day01Suite.scala

@@ -1,14 +1,35 @@
 import Day01.*
 import Day01Suite.*
 import munit.ScalaCheckSuite
-import org.scalacheck.Gen
-import org.scalacheck.Prop.*
 
 class Day01Suite extends ScalaCheckSuite:
 
-  test("day01 == 42"):
-    assertEquals(day01, 42)
+  test("parse small input"):
+    assertEquals(
+      Input.parse(smallInput),
+      Some(
+        Input(
+          left = List(3, 4, 2, 1, 3, 3).map(LocationId(_)),
+          right = List(4, 3, 5, 3, 9, 3).map(LocationId(_))
+        )
+      )
+    )
+
+  test("total distance for small input is 11"):
+    assertEquals(totalDistance(smallInput), Some(11L))
+
+  test("total distance for big input is 1_223_326"):
+    assertEquals(totalDistance(bigInput), Some(1_223_326L))
 
 object Day01Suite:
 
   val bigInput: List[String] = getLinesFromFile("src/test/scala/day01_input.txt")
+
+  val smallInput: List[String] = List(
+    "3   4",
+    "4   3",
+    "2   5",
+    "1   3",
+    "3   9",
+    "3   3"
+  )