day 8 puzzle 1

README.md

@@ -5,11 +5,11 @@ This repo contains my attempt at this year's Advent of Code (2023)
 I will try and do some problems (probably not all of them) in Scala
 
 ## Progress:
-#### Stars: 14 / 50
+#### Stars: 15 / 50
 |        Mon        |        Tue        |        Wed        |        Thu        |        Fri        |        Sat        |        Sun        |
 |:-----------------:|:-----------------:|:-----------------:|:-----------------:|:-----------------:|:-----------------:|:-----------------:|
 |                   |                   |                   |                   | 1<br>:star::star: | 2<br>:star::star: | 3<br>:star::star: |
-| 4<br>:star::star: | 5<br>:star::star: | 6<br>:star::star: | 7<br>:star::star: |         8         |         9         |        10         |
+| 4<br>:star::star: | 5<br>:star::star: | 6<br>:star::star: | 7<br>:star::star: |    8<br>:star:    |         9         |        10         |
 |        11         |        12         |        13         |        14         |        15         |        16         |        17         |
 |        18         |        19         |        20         |        21         |        22         |        23         |        24         |
 |        25         |                   |                   |                   |                   |                   |                   |

src/day8/Node.scala

@@ -0,0 +1,5 @@
+package day8
+
+class Node(val id: String, val nextNodes: Array[String]) {
+
+}

src/day8/Puzzle1.scala

@@ -0,0 +1,47 @@
+package day8
+
+import scala.collection.mutable
+import scala.io.{BufferedSource, Source}
+import scala.util.matching.Regex
+import scala.util.matching.Regex.Match
+
+object Puzzle1 {
+  var rule: Array[Int] = Array.empty
+  val nodes: mutable.Map[String, Node] = new mutable.HashMap()
+  def loadInput(path: String): Unit = {
+    val source: BufferedSource = Source.fromFile(path)
+    val lines: String = source.getLines().mkString("\n")
+    val parts: Array[String] = lines.split("\n\n")
+
+    rule = parts(0).map(c => "LR".indexOf(c)).toArray
+    val regexp: Regex = new Regex("([A-Z]{3}) = \\(([A-Z]{3}), ([A-Z]{3})\\)")
+    for (line: String <- parts(1).split("\n")) {
+      val matches: Match = regexp.findFirstMatchIn(line).get
+      val id: String = matches.group(1)
+      val left: String = matches.group(2)
+      val right: String = matches.group(3)
+      nodes(id) = new Node(id, Array(left, right))
+    }
+
+    source.close()
+  }
+
+  def solve(path: String): Int = {
+    loadInput(path)
+
+    var solution: Int = 0
+    var id: String = "AAA"
+
+    while (id != "ZZZ") {
+      id = nodes(id).nextNodes(rule(solution % rule.length))
+      solution += 1
+    }
+
+    return solution
+  }
+
+  def main(args: Array[String]): Unit = {
+    val solution: Int = solve("./res/day8/input1.txt")
+    println(solution)
+  }
+}

tests/day8/Puzzle1Test.scala

@@ -0,0 +1,9 @@
+package day8
+
+import org.scalatest.funsuite.AnyFunSuite
+
+class Puzzle1Test extends AnyFunSuite {
+  test("Puzzle1.solve") {
+    assert(Puzzle1.solve("tests_res/day8/input1.txt") == 6)
+  }
+}

tests_res/day8/input1.txt

@@ -0,0 +1,5 @@
+LLR
+
+AAA = (BBB, BBB)
+BBB = (AAA, ZZZ)
+ZZZ = (ZZZ, ZZZ)