From b060f3f3925754a157f6f152209c54d30cdd37c7 Mon Sep 17 00:00:00 2001
From: Jay Foad <jay.foad@gmail.com>
Date: Mon, 17 Dec 2018 11:27:21 +0000
Subject: [PATCH] Day 9 solution using a doubly linked list.

---
 p9.txt        |  1 +
 p9list.dyalog | 10 ++++++++++
 2 files changed, 11 insertions(+)
 create mode 100644 p9.txt
 create mode 100644 p9list.dyalog

diff --git a/p9.txt b/p9.txt
new file mode 100644
index 0000000..aa93dd2
--- /dev/null
+++ b/p9.txt
@@ -0,0 +1 @@
+470 players; last marble is worth 72170 points
diff --git a/p9list.dyalog b/p9list.dyalog
new file mode 100644
index 0000000..9c5e88e
--- /dev/null
+++ b/p9list.dyalog
@@ -0,0 +1,10 @@
+⎕IO←0
+(p w)←⍎¨'\d+'⎕S'&'⊃⊃⎕NGET'p9.txt'1
+
+ins←{q←(p←⍵ 1⌷m)1⌷m ⋄ n←m[(p 1)(q 0)]←≢m ⋄ m⍪←p q ⋄ n}
+del←{f←{⍵ 0⌷m} ⋄ p←f(r,←f(q←f⍣6⊢⍵)) ⋄ m[(p 1)(q 0)]←q p ⋄ m⍪←0 ⋄ q}
+run←{ins⍣(23|⍵)del∘(ins⍣22)⍣(⌊⍵÷23)⊢0}
+hscore←{⌈/+⌿z⍵⍴(⍵×z←⌈⍵÷⍨≢r)↑r+23×1+⍳≢r}
+
+r←⍬ ⋄ m←1 2⍴0 ⋄ (hscore p)⊣run w ⍝ part 1
+r←⍬ ⋄ m←1 2⍴0 ⋄ (hscore p)⊣run w×100 ⍝ part 2