From 2190f9e1ac81fec68b9179b6a341cf5cdf13eedb Mon Sep 17 00:00:00 2001
From: chrisly42 <chrisly@platon42.de>
Date: Thu, 11 Dec 2025 07:55:54 +0100
Subject: [PATCH] No need to have two different recursion functions for Day 11.
 Tidied up.

---
 src/aoc2025/Day11.kt | 49 ++++++++++++++++----------------------------
 1 file changed, 18 insertions(+), 31 deletions(-)

diff --git a/src/aoc2025/Day11.kt b/src/aoc2025/Day11.kt
index 7b5db4e..bec5e34 100644
--- a/src/aoc2025/Day11.kt
+++ b/src/aoc2025/Day11.kt
@@ -38,16 +38,6 @@ ggg: out
 hhh: out
 """
 
-    data class Node(val name: String, val children: Set<Node>)
-
-    fun rec(children: HashMap<String, MutableSet<String>>, p: String, visited: MutableSet<String>): Int {
-        if (p == "out") return 1
-        visited.add(p)
-        val res = children[p]!!.sumOf { rec(children, it, visited) }
-        visited.remove(p)
-        return res
-    }
-
     fun parseInput(input: List<String>): HashMap<String, MutableSet<String>> {
         val children = HashMap<String, MutableSet<String>>()
         for (i in input) {
@@ -58,13 +48,7 @@ hhh: out
         return children
     }
 
-    fun part1(input: List<String>): Int {
-        val children = parseInput(input)
-
-        return rec(children, "you", HashSet())
-    }
-
-    fun rec2(
+    fun rec(
         children: HashMap<String, MutableSet<String>>,
         p: String,
         stop: String,
@@ -72,24 +56,27 @@ hhh: out
         memo: HashMap<String, Long> = HashMap()
     ): Long {
         if (p == stop) return 1L
-        val memoVal = memo[p]
-        if (memoVal != null) return memoVal
-        visited.add(p)
-        val res = children[p]?.sumOf { rec2(children, it, stop, visited, memo) } ?: 0L
-        visited.remove(p)
-        memo[p] = res
-        return res
+        return memo.getOrPut(p) {
+            visited.add(p)
+            val res = children[p]?.sumOf { rec(children, it, stop, visited, memo) } ?: 0L
+            visited.remove(p)
+            res
+        }
+    }
+
+    fun part1(input: List<String>): Long {
+        return rec(parseInput(input), "you", "out")
     }
 
     fun part2(input: List<String>): Long {
         val children = parseInput(input)
 
-        val srvToDac = rec2(children, "svr", "dac")
-        val dacToFft = rec2(children, "dac", "fft")
-        val fftToOut = rec2(children, "fft", "out")
-        val srvToFft = rec2(children, "svr", "fft")
-        val fftToDac = rec2(children, "fft", "dac")
-        val dacToOut = rec2(children, "dac", "out")
+        val srvToDac = rec(children, "svr", "dac")
+        val dacToFft = rec(children, "dac", "fft")
+        val fftToOut = rec(children, "fft", "out")
+        val srvToFft = rec(children, "svr", "fft")
+        val fftToDac = rec(children, "fft", "dac")
+        val dacToOut = rec(children, "dac", "out")
 
         return srvToDac * dacToFft * fftToOut + srvToFft * fftToDac * dacToOut
     }
@@ -102,7 +89,7 @@ hhh: out
     println("Part 1 Test: $testInputPart1Result")
     val testInputPart2Result = part2(testInput2)
     println("Part 2 Test: $testInputPart2Result")
-    check(testInputPart1Result == 5)
+    check(testInputPart1Result == 5L)
     check(testInputPart2Result == 2L)
 
     val input = readInput("aoc2025/Day11")