feat(sterni/aoc/2022): day08 BQN solution

Added utility used to be related, but got dropped in a refactor.

Change-Id: I1f88973d6b42f1302b49cd61c53e4cd1e15b8c6f
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7553
Autosubmit: sterni <sternenseemann@systemli.org>
Reviewed-by: sterni <sternenseemann@systemli.org>
Tested-by: BuildkiteCI

users/sterni/exercises/aoc/2022/08/8.bqn

@@ -0,0 +1,15 @@
+i ← >'0'-˜•FLines "input"
+Visible ← {
+  _vis ← {(⌈`∘(¯1⊸»˘⌾⍉)<⊢)⌾𝕏 𝕗}
+  ∨´𝕩 _vis¨ ⟨⊢,⌽,⍉,⌽⍉⟩
+}
+
+•Out "day08.1: "∾•Fmt +´⥊Visible i
+
+ViewingDistances ← {
+  DirView ← {≠1(»⟜(∧`(⊑𝕩)⊸>)/⊢) 1↓𝕩}
+  _spliceDir ← {! =´≢𝕗 ⋄ 𝕏⁼(⊢↓(⊏⟜(𝕏𝕗))∘⊣)´¨ ⋈⌜˜↕≠𝕗}
+  ×´ DirView¨¨ 𝕩 _spliceDir¨ ⟨⊢, ⌽˘, ⍉, ⌽˘⍉⟩
+}
+
+•Out "day08.2: "∾•Fmt ⌈´⥊ViewingDistances i

users/sterni/exercises/aoc/lib.bqn

@@ -4,5 +4,6 @@ ReadInt ⇐ {(𝕨⊸×+⊣)´∘⌽-⟜'0'𝕩} # stolen from leah2
 ReadDec ⇐ 10⊸ReadInt
 
 SplitOn ⇐ ((⊢ (-1˙)⍟⊣¨ +`∘(1⊸»<⊢))∘(≡¨)⊔⊢)
+SplitAt ← ((⊣≤↕∘≠∘⊢)⊔⊢)
 
 _fix ⇐ {𝕩 𝕊∘⊢⍟≢ 𝔽 𝕩}