2024-10 Scala 2

scala2/src/main/resources/2024/10-test-00.txt

@@ -0,0 +1,8 @@
+89010123
+78121874
+87430965
+96549874
+45678903
+32019012
+01329801
+10456732

scala2/src/main/resources/2024/10.txt

@@ -0,0 +1,60 @@
+670107898789217654342123456782345678011256767898765465432101
+789234567654308210256034105891089019100349897767874376569101
+658341234530989300107845234521078323270110588758901287478272
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scala2/src/main/scala/jurisk/adventofcode/y2024/Advent10.scala

@@ -1,37 +1,66 @@
 package jurisk.adventofcode.y2024
 
+import jurisk.geometry.{Coords2D, Field2D}
 import jurisk.utils.FileInput._
 import jurisk.utils.Parsing.StringOps
 
 object Advent10 {
-  type Input = List[Command]
+  type Input = Field2D[Int]
   type N     = Long
 
-  sealed trait Command extends Product with Serializable
-  object Command {
-    case object Noop                      extends Command
-    final case class Something(
-      values: List[N]
-    ) extends Command
-    final case class Other(value: String) extends Command
-
-    def parse(s: String): Command =
-      s match {
-        case "noop"            => Noop
-        case s"something $rem" => Something(rem.extractLongList)
-        case s if s.nonEmpty   => Other(s)
-        case _                 => s.failedToParse
+  private val Start  = 0
+  private val Finish = 9
+
+  def parse(input: String): Input =
+    Field2D.parseDigitField(input)
+
+  private def countReachableEnds(data: Input, from: Coords2D): Int = {
+    def reachableEnds(data: Input, c: Coords2D, current: Int): Set[Coords2D] =
+      if (current == Finish) {
+        Set(c)
+      } else {
+        val next = current + 1
+        data
+          .neighboursFor(c, includeDiagonal = false)
+          .filter(n => data.at(n).contains(next))
+          .flatMap { n =>
+            reachableEnds(data, n, next)
+          }
+          .toSet
       }
+
+    reachableEnds(data, from, 0).size
   }
 
-  def parse(input: String): Input =
-    input.parseLines(Command.parse)
+  private def countDistinctPaths(
+    data: Input,
+    c: Coords2D,
+    current: Int = Start,
+  ): Int =
+    if (current == Finish) {
+      1
+    } else {
+      val next = current + 1
+      data
+        .neighboursFor(c, includeDiagonal = false)
+        .filter(n => data.at(n).contains(next))
+        .map { n =>
+          countDistinctPaths(data, n, next)
+        }
+        .sum
+    }
+
+  private def solve(data: Input, f: (Input, Coords2D) => Int): Int = {
+    val candidateTrailHeads = data.filterCoordsByValue(_ == Start)
+    val scores              = candidateTrailHeads.map(c => f(data, c))
+    scores.sum
+  }
 
   def part1(data: Input): N =
-    0
+    solve(data, countReachableEnds)
 
   def part2(data: Input): N =
-    0
+    solve(data, (data, c) => countDistinctPaths(data, c))
 
   def parseFile(fileName: String): Input =
     parse(readFileText(fileName))

scala2/src/test/scala/jurisk/adventofcode/y2024/Advent10Spec.scala

@@ -10,21 +10,21 @@ class Advent10Spec extends AnyFreeSpec {
 
   "part 1" - {
     "test" in {
-      part1(testData) shouldEqual 0
+      part1(testData) shouldEqual 36
     }
 
     "real" in {
-      part1(realData) shouldEqual 0
+      part1(realData) shouldEqual 811
     }
   }
 
   "part 2" - {
     "test" in {
-      part2(testData) shouldEqual 0
+      part2(testData) shouldEqual 81
     }
 
     "real" in {
-      part2(realData) shouldEqual 0
+      part2(realData) shouldEqual 1794
     }
   }
 }