From 63c07061a2dd1f4067ba215d41bb7254f1a29dba Mon Sep 17 00:00:00 2001
From: Leah Neukirchen <leah@vuxu.org>
Date: Sun, 19 Dec 2021 17:21:15 +0100
Subject: day18

---
 day18.bqn | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)
 create mode 100644 day18.bqn

(limited to 'day18.bqn')

diff --git a/day18.bqn b/day18.bqn
new file mode 100644
index 0000000..c469fa7
--- /dev/null
+++ b/day18.bqn
@@ -0,0 +1,27 @@
+d ← {•BQN ("⟨⟩"∾𝕩) ⊏˜ ("[]"∾𝕩) ⊐ 𝕩}¨•FLines"day18"
+
+Split ← { 𝕊 ⟨l,r⟩: { 𝕊 @: { 𝕊 @: @ ; 𝕊 r2: l‿r2 } Split r ;
+                     𝕊 l2: l2‿r } Split l ;
+          𝕊 n: n ≥ 10 ? (⌊⋈⌈) n÷2 ;
+          @ }
+
+Addlm ← { n 𝕊 ⟨l,r⟩: ⟨n Addlm l, r⟩ ; n 𝕊 m : n + m }
+Addrm ← { n 𝕊 ⟨l,r⟩: ⟨l, n Addrm r⟩ ; n 𝕊 m : n + m }
+
+Explode ← {
+  4 𝕊 ⟨l,r⟩: 0‿l‿r ;
+  d 𝕊 ⟨l,r⟩: { 𝕊 @: { 𝕊 @: @ ;
+                       𝕊 ⟨r2,ln,rn⟩: ⟨ln Addrm l,r2⟩‿0‿rn } (d+1) Explode r ;
+               𝕊 ⟨l2,ln,rn⟩: ⟨l2,rn Addlm r⟩‿ln‿0 } (d+1) Explode l ;
+  @
+}
+
+Reduce ← { 𝕊 t: { 𝕊 @: { 𝕊 @: t ; 𝕊 t3: Reduce t3 } Split t ;
+                  𝕊 t2: Reduce t2 } ⊑ 0 Explode t }
+
+Add ← Reduce∘⋈
+
+Mag ← { 𝕊 ⟨l,r⟩: (3×Mag l)+(2×Mag r) ; 𝕊 n: n }
+
+•Show Mag Add˜´ ⌽ d
+•Show ⌈´⥊Mag∘Add⌜˜ d
-- 
cgit 1.4.1