2024 - Day 10 - refactored after talking with chriswk.

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

@@ -11,32 +11,23 @@ class Day10(val input: List<String>) : Day<Int, Int, Map<Pos, Int>> {
     private val heads = grid.filterValues { it == 0 }.keys
 
     override fun partOne(): Int {
-        return heads.sumOf { it.score(mutableSetOf()) }
+        return heads.sumOf {
+            it.score().toSet().size
+        }
     }
 
     override fun partTwo(): Int {
-        return heads.sumOf { it.rating(emptyList(), mutableSetOf()) }
+        return heads.sumOf {
+            it.score().size
+        }
     }
 
-    // part 1
-    private fun Pos.score(visited: MutableSet<Pos>): Int {
+    private fun Pos.score(): List<Pos> {
         val c = grid[this]!!
-        visited.add(this)
-        return if (c == 9) 1
-        else neighbourCellsUDLR().filterNot { it in visited }
+        return if (c == 9) listOf(this)
+        else neighbourCellsUDLR()
             .filter { grid[it] == c + 1 }
-            .sumOf { it.score(visited) }
-    }
-
-    // part 2
-    private fun Pos.rating(path: List<Pos>, visited: MutableSet<List<Pos>>): Int {
-        val c = grid[this]!!
-        val newPath = path + this
-        visited.add(newPath)
-        return if (c == 9) 1
-        else neighbourCellsUDLR().filterNot { (newPath + it) in visited }
-            .filter { grid[it] == c + 1 }
-            .sumOf { it.rating(newPath, visited) }
+            .flatMap { it.score() }
     }
 
     override fun List<String>.parse(): Map<Pos, Int> {
@@ -48,7 +39,6 @@ class Day10(val input: List<String>) : Day<Int, Int, Map<Pos, Int>> {
     }
 
     override val day = "10".toInt()
-
 }
 
 

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

@@ -30,7 +30,7 @@ internal class Day10Test {
         { Day10(data10) },
         { Day10(test10) },
         numTestPart1 = 200,
-        numTestPart2 = 50,
+        numTestPart2 = 200,
     )
 
     @Nested