finish day08

Author: Emre Akgül (CarTelSol)

README.md

@@ -1,6 +1,6 @@
 ![Kotlin](https://img.shields.io/badge/Kotlin-grey?logo=Kotlin&style=for-the-badge)
-![](https://img.shields.io/badge/📅%20days-04-005060?style=for-the-badge)
-![](https://img.shields.io/badge/⭐%20stars-06-005060?style=for-the-badge)
+![](https://img.shields.io/badge/📅%20days-08-005060?style=for-the-badge)
+![](https://img.shields.io/badge/⭐%20stars-16-005060?style=for-the-badge)
 
 # Advent-of-Code 2023
 

src/main/kotlin/tr/emreone/adventofcode/days/Day08.kt

@@ -0,0 +1,74 @@
+package tr.emreone.adventofcode.days
+
+import tr.emreone.kotlin_utils.Resources
+import tr.emreone.kotlin_utils.automation.Day
+import tr.emreone.kotlin_utils.lcm
+import java.lang.IllegalStateException
+
+class Day08 : Day(
+    8,
+    2023,
+    "Haunted Wasteland",
+    session = Resources.resourceAsString("session.cookie")
+) {
+
+    private fun parseInput(): Pair<List<Int>, Map<String, List<String>>> {
+        val command = inputAsList[0].toCharArray().map { if (it == 'L') 0 else 1 }
+        val maps = inputAsList.drop(2).associate {
+            val (key, value) = it.split("=")
+
+            val destinations = value
+                .trim()
+                .trimStart('(')
+                .trimEnd(')')
+                .split(',')
+                .map {
+                    it.trim()
+                }
+
+            key.trim() to destinations
+        }
+
+        return command to maps
+    }
+
+    override fun part1(): Int {
+        val (command, maps) = parseInput()
+        var currentPosition ="AAA"
+
+        var counter = 0
+        val totalCommands = command.size
+        while(currentPosition != "ZZZ") {
+            val index = (counter.mod(totalCommands))
+            // print("%6d: $currentPosition to ($index -> ${ if (command[index] == 0) 'L' else 'R'}) ".format(counter))
+            currentPosition = maps[currentPosition]?.get(command[index]) ?: throw IllegalStateException()
+            // println(currentPosition)
+            counter++
+        }
+
+        return counter
+    }
+
+    override fun part2(): Long {
+        val (command, maps) = parseInput()
+        val startPositions = maps.keys.filter { it.endsWith('A') }.toMutableList()
+
+        val totalCommands = command.size
+
+        val steps = startPositions.map {
+            var currentPosition = it
+
+            var counter = 0L
+            while(!currentPosition.endsWith('Z')) {
+                val index = (counter.mod(totalCommands))
+                currentPosition = maps[currentPosition]?.get(command[index]) ?: throw IllegalStateException()
+                counter++
+            }
+
+            counter
+        }
+
+        return steps.lcm()
+    }
+
+}

src/test/kotlin/tr/emreone/adventofcode/days/Day08Test.kt

@@ -0,0 +1,16 @@
+package tr.emreone.adventofcode.days
+
+import tr.emreone.kotlin_utils.Resources
+import tr.emreone.kotlin_utils.automation.solve
+
+fun main() {
+    solve<Day08>(false) {
+        Resources.resourceAsList("day08_1_example.txt")
+            .joinToString("\n") part1 6
+    }
+
+    solve<Day08>(false) {
+        Resources.resourceAsList("day08_2_example.txt")
+            .joinToString("\n") part2 6
+    }
+}