2024 - Day 10 - part 1

src/main/kotlin/no/rodland/advent_2024/Day10.kt

@@ -1,27 +1,54 @@
 package no.rodland.advent_2024
 
 import no.rodland.advent.Day
+import no.rodland.advent.Pos
 
 // template generated: 10/12/2024
 // Fredrik Rødland 2024
-
-class Day10(val input: List<String>) : Day<Long, Long, List<String>> {
+class Day10(val input: List<String>) : Day<Int, Long, Pair<Pair<Set<Pos>, Set<Pos>>, Array<CharArray>>> {
 
     private val parsed = input.parse()
+    private val heads = parsed.first.first
+    private val tails = parsed.first.second
+    private val grid = parsed.second
 
-    override fun partOne(): Long {
-        return 2
+    override fun partOne(): Int {
+        return heads.sumOf { it.score(mutableSetOf()) }
     }
 
     override fun partTwo(): Long {
         return 2
     }
 
-    override fun List<String>.parse(): List<String> {
-        return map { line ->
-            line
-        }
+    private fun Pos.score(visited: MutableSet<Pos>): Int {
+        visited.add(this)
+        val c = grid[this].digitToInt()
+        return if (c == 9) return 1
+        else neighbourCellsUDLR()
+            .filterNot { it in visited }
+            .filter { it in grid }
+            .filter { grid[it].digitToInt() == c + 1 }
+            .sumOf { it.score(visited) }
+    }
+
+    operator fun Grid.contains(pos: Pos): Boolean = pos.x >= 0 && pos.x < this[0].size && pos.y >= 0 && pos.y < this.size
+
+    operator fun Grid.get(pos: Pos): Char = this[pos.y][pos.x]
+
+    override fun List<String>.parse(): Pair<Pair<Set<Pos>, Set<Pos>>, Array<CharArray>> {
+        val heads = mutableSetOf<Pos>()
+        val tails = mutableSetOf<Pos>()
+        val grid = indices.map { y ->
+            indices.map { x ->
+                val c = this[y][x]
+                if (c == '0') heads.add(Pos(x, y))
+                if (c == '9') tails.add(Pos(x, y))
+                c
+            }.toCharArray()
+        }.toTypedArray()
+        return (heads to tails) to grid
     }
 
     override val day = "10".toInt()
 }
+

src/test/kotlin/no/rodland/advent_2024/Day10Test.kt

@@ -15,9 +15,9 @@ internal class Day10Test {
     private val data10 = "2024/input_10.txt".readFile()
     private val test10 = "2024/input_10_test.txt".readFile()
 
-    private val resultTestOne = 2L
+    private val resultTestOne = 36
     private val resultTestTwo = 2L
-    private val resultOne = 2L
+    private val resultOne = 514
     private val resultTwo = 2L
 
     val test = defaultTestSuiteParseOnInit(
@@ -29,6 +29,7 @@ internal class Day10Test {
         resultTwo,
         { Day10(data10) },
         { Day10(test10) },
+        numTestPart1 = 200
     )
 
     @Nested