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+jets ← '>'= "<>" (∊˜/⊢) •FChars "input"
+pieces ← >¨⟨1‿1‿1‿1⟩‿⟨0‿1‿0,1‿1‿1,0‿1‿0⟩‿⟨0‿0‿1,0‿0‿1,1‿1‿1⟩‿⟨⋈1,⋈1,⋈1,⋈1⟩‿⟨1‿1,1‿1⟩
+w ← 7
+initial ← 0‿w⥊0
+
+# Warning: mutated global!
+ji ← 0
+_try ← {(⊢ 𝕩˙⍟(≠○(+´∘⥊∘∨⟜𝕨)) 𝔽) 𝕩}
+Fall ← {
+  pushed ← 𝕨 ((ji⊑jets)◶«‿»)˘ _try 𝕩
+  ji ↩ (≠jets)|ji+1
+  fallen ← 𝕨 » _try pushed
+  𝕨 𝕊⍟(pushed≢fallen) fallen
+}
+Height ← ≠∘(∨´˘/⊢)
+ThrowPiece ← {
+  piece ← 𝕩 (|˜⟜≠⊑⊢) pieces
+  chamber ← (((3+≠piece)⊸+∘⊑∘(1⊸↑)∘⌽∘(1⊸+)∘/∨´˘)↑⊢)⌾⌽𝕨
+  falling ← (≠chamber)↑(»⍟2 w⊸↑)˘piece
+  chamber (⊣∨Fall) falling
+}
+
+•Out "day17.1: "∾•Fmt Height initial ThrowPiece˜´ ⌽↕2022
+
+# https://mlochbaum.github.io/BQN/doc/control.html#while
+While ← {𝕩{𝔽⍟𝔾∘𝔽_𝕣_𝔾∘𝔽⍟𝔾𝕩}𝕨@}´
+{
+  target ← 1000000000000
+  ji ↩ 0 ⋄ i ← 0 ⋄ res ← @
+
+  chamber ← initial
+  cycles ← ⟨≠pieces,≠jets⟩⥊<⟨⟩
+
+  While {𝕤⋄res=@}‿{𝕤
+    chamber ↩ chamber ThrowPiece i
+    i +↩ 1
+
+    t ← i|˜≠pieces
+    cycles ↩ {
+      new ← 𝕩∾<i⋈Height chamber
+      res ↩ {𝕊 𝕩:
+        ⟨pl,hl⟩‿· ← chk ← ¯2↑new
+        pd‿hd ← -´⌽chk
+        @˙⍟(0≠pd|target-pl) hl+hd×pd÷˜target-pl
+      }⍟(1<≠new) @
+      new
+    }⌾(t‿ji⊸⊑) cycles
+  }
+
+  •Out "day17.2: "∾•Fmt res
+}