$ RL
$
$ AAA = (BBB, CCC)
$ BBB = (DDD, EEE)
$ CCC = (ZZZ, GGG)
$ DDD = (DDD, DDD)
$ EEE = (EEE, EEE)
$ GGG = (GGG, GGG)
$ ZZZ = (ZZZ, ZZZ)
TestInput ←

$ LLR
$
$ AAA = (BBB, BBB)
$ BBB = (AAA, ZZZ)
$ ZZZ = (ZZZ, ZZZ)
TestInputII ←

$ LR
$
$ 11A = (11B, XXX)
$ 11B = (XXX, 11Z)
$ 11Z = (11B, XXX)
$ 22A = (22B, XXX)
$ 22B = (22C, 22C)
$ 22C = (22Z, 22Z)
$ 22Z = (22B, 22B)
$ XXX = (XXX, XXX)
TestInputIII ←

ParseI ← (
  ⊓⊢≡(°[⊙⊙∘]≡°□↘1⊢regex"(.{3}) = \\((.{3}), (.{3})\\)")∩≡°□⊃↙↘1⊜□≠@\n.
  ⊙⊙⊙⊟⊃(∘|°⊟⊗"AAA"_"ZZZ"⋅∘|⊗:⋅⊙∘|⊗:⋅⊙⋅∘)
)

ParseII ← (
  ⊓⊢≡(°[⊙⊙∘]≡°□↘1⊢regex"(.{3}) = \\((.{3}), (.{3})\\)")∩≡°□⊃↙↘1⊜□≠@\n.
  ⊙⊙⊙⊟⊃(∘|°⊟≡(⊚⌕)"AZ"¤≡(⊢⇌)⋅∘|⊗:⋅⊙∘|⊗:⋅⊙⋅∘)
)

PartI ← ⊙⋅⋅⋅;⍢⊃(
  +1
| ⋅∘
| ⊡⊟⊗⊙"LR"⊡◿⧻,⊙⊙⊙⋅∘
| ⋅⋅⋅⊙∘
)(¬∊⋅⋅⊙∘) 0

Lcm ← ×÷⊃(+⍢⊃◿∘(≠0×)⊃↧↥|⊙∘)
PartII ← /Lcm≡(PartI)¤⊙⊙∩¤

PartI ParseI TestInput
PartI ParseI TestInputII
PartII ParseII TestInputIII

PartI ParseI &fras "day08.in"
PartII ParseII &fras "day08.in"