From 54709e41f5f902d6f108f48f7513f8dfa43a04f7 Mon Sep 17 00:00:00 2001
From: kageru <kageru@encode.moe>
Date: Fri, 6 Dec 2019 11:48:19 +0100
Subject: [PATCH] D6: Improve performance for long graphs

---
 2019/06/day06.kt | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/2019/06/day06.kt b/2019/06/day06.kt
index 1309b4d..da0f673 100644
--- a/2019/06/day06.kt
+++ b/2019/06/day06.kt
@@ -6,7 +6,7 @@ fun main() {
     val childToParent = input.associateBy { it[1] }.mapValues { it.value[0] }
     val santaParents = getParents(childToParent, "SAN")
     val myParents = getParents(childToParent, "YOU")
-    val commonParent = santaParents.first { it in myParents }
+    val commonParent = myParents.toSet().let { s -> santaParents.first { it in s } }
     println("Part 2: ${santaParents.indexOf(commonParent) + myParents.indexOf(commonParent)}")
 }