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-rw-r--r--users/sterni/exercises/aoc/2022/09/9.bqn17
1 files changed, 17 insertions, 0 deletions
diff --git a/users/sterni/exercises/aoc/2022/09/9.bqn b/users/sterni/exercises/aoc/2022/09/9.bqn
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+++ b/users/sterni/exercises/aoc/2022/09/9.bqn
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+⟨SplitOn,ReadDec⟩ ← •Import "../../lib.bqn"
+i ← ReadDec⌾(1⊸⊑)¨ (<' ')⊸SplitOn¨ •FLines "input"
+
+UnitDelta ← (⊢÷(|+0⊸=))
+ExpandStep ← {
+  𝕊 "L"‿l: 𝕊 (-l)‿0;
+  𝕊 "R"‿r: 𝕊 r‿0;
+  𝕊 "U"‿u: 𝕊 0‿u;
+  𝕊 "D"‿d: 𝕊 0‿(-d);
+  𝕊 delta: ((⌈´|)⥊<∘UnitDelta) delta
+}
+
+Step ← {knots 𝕊 delta: {h 𝕊 t: (UnitDelta h-t) +⍟(1<⌈´|h-t) t}` (delta⊸+)⌾⊑ knots}
+Visited ← {+´0=⊒(¯1⊸⊑)¨(<𝕨⥊<0‿0) Step` ∾ExpandStep¨ 𝕩}
+
+•Out "day09.1: "∾•Fmt  2 Visited i
+•Out "day09.2: "∾•Fmt 10 Visited i