From 2470b4e8ff867eded474d643171914455364c0c3 Mon Sep 17 00:00:00 2001
From: Ben Harris <bjh21@bjh21.me.uk>
Date: Sun, 12 May 2024 11:57:52 +0100
Subject: [PATCH] 12: factorise contruction of can_go_x arrays somewhat

---
 12/12a.bqn | 10 ++++------
 12/12b.bqn | 10 ++++------
 2 files changed, 8 insertions(+), 12 deletions(-)

diff --git a/12/12a.bqn b/12/12a.bqn
index f0ebe28..69790d1 100644
--- a/12/12a.bqn
+++ b/12/12a.bqn
@@ -5,12 +5,10 @@ Prep←{
 }
 
 Main←{𝕊⟨start,end,map⟩:
-  can_go_n←1≥(»map)-map
-  can_go_s←1≥(«map)-map
-  can_go_w←1≥(»˘map)-map
-  can_go_e←1≥(«˘map)-map
-  Flow←{
-    𝕩∨(«𝕩∧can_go_n)∨(»𝕩∧can_go_s)∨(«˘𝕩∧can_go_w)∨(»˘𝕩∧can_go_e)
+  shifts←⟨«,«˘,»˘,»⟩
+  can_go←{1≥(𝕏map)-map}¨shifts
+  Flow←{𝕊now:
+    now∨´can_go{𝕏now∧𝕨}¨⌽shifts
   }
   count←0
   {count+↩1 ⋄ Flow 𝕩} •_while_ {¬∨´⥊(𝕩∧end)} start
diff --git a/12/12b.bqn b/12/12b.bqn
index d92f7c9..66163c3 100644
--- a/12/12b.bqn
+++ b/12/12b.bqn
@@ -6,12 +6,10 @@ Prep←{
 }
 
 Main←{𝕊⟨start,end,map⟩:
-  can_go_n←1≥(»map)-map
-  can_go_s←1≥(«map)-map
-  can_go_w←1≥(»˘map)-map
-  can_go_e←1≥(«˘map)-map
-  Flow←{
-    𝕩∨(«𝕩∧can_go_n)∨(»𝕩∧can_go_s)∨(«˘𝕩∧can_go_w)∨(»˘𝕩∧can_go_e)
+  shifts←⟨«,«˘,»˘,»⟩
+  can_go←{1≥(𝕏map)-map}¨shifts
+  Flow←{𝕊now:
+    now∨´can_go{𝕏now∧𝕨}¨⌽shifts
   }
   count←0
   {count+↩1 ⋄ Flow 𝕩} •_while_ {¬∨´⥊(𝕩∧end)} start
-- 
2.30.2