89 lines
2.8 KiB
Plaintext
89 lines
2.8 KiB
Plaintext
load "bool.quox"
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load "list.quox"
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load "maybe.quox"
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load "int.quox"
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def zz = int.zeroℤ
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def step : ω.(List ℤ) → List ℤ =
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λ xs ⇒
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list.zip-with-uneven ℤ ℤ ℤ (λ m n ⇒ int.minus n m)
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xs (list.tail-or-nil ℤ xs)
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def all-zero : ω.(List ℤ) → Bool =
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list.foldlω ℤ Bool 'true (λ b n ⇒ bool.and b (int.eq n zz))
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def last : 0.(A : ★) → ω.(List A) → Maybe A =
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λ A ⇒ list.foldrω A (Maybe A) (Nothing A) (λ x y ⇒ maybe.or A y (Just A x))
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def0 last-ok : last ℕ (4, 1, 4, 8, 5, 'nil) ≡ Just ℕ 5 : Maybe ℕ =
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δ 𝑖 ⇒ Just ℕ 5
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def last-or-0 : ω.(List ℤ) → ℤ =
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λ xs ⇒ maybe.fold ℤ ℤ zz (λ x ⇒ x) (last ℤ xs)
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{-
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def next-entries : ω.(List ℕ) → List ℕ =
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λ xs ⇒
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letω fuel = fst xs in
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caseω fuel return ω.(List ℕ) → List ℕ of {
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0 ⇒ λ _ ⇒ list.Nil ℕ;
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succ _, ω.rec ⇒ λ this ⇒
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bool.if (List ℕ) (all-zero this) (list.Nil ℕ)
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(letω next : List ℕ = step this in
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letω rest : List ℕ = rec next in
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letω new : ℕ = nat.plus (last-or-0 this) (head-or-0 rest) in
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list.Cons ℕ new rest)
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} xs
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-}
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def next-entry : ω.(List ℕ) → ℕ =
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λ xs ⇒
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letω fuel = fst xs in
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letω xs = list.map ℕ ℤ int.from-ℕ xs in
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let result : ℤ =
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caseω fuel return ω.(List ℤ) → ℤ of {
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0 ⇒ λ _ ⇒ zz;
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succ _, ω.rec ⇒ λ this ⇒
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bool.if ℤ (all-zero this) zz
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(letω next : List ℤ = step this in
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letω diff : ℤ = rec next in
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int.plus diff (last-or-0 this))
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} xs in
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int.abs result
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def0 ok-1 : next-entry (6, 0, 3, 6, 9, 12, 15, 'nil) ≡ 18 : ℕ = δ _ ⇒ 18
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def0 ok-2 : next-entry (6, 1, 3, 6, 10, 15, 21, 'nil) ≡ 28 : ℕ = δ _ ⇒ 28
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def0 ok-3 : next-entry (6, 10, 13, 16, 21, 30, 45, 'nil) ≡ 68 : ℕ = δ _ ⇒ 68
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load "io.quox"
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load "string.quox"
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def read-file : ω.String → IO [ω.List (List ℕ)] =
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λ path ⇒
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letω split-lines : ω.String → List String =
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string.split (λ c ⇒ char.eq c char.newline);
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split-numbers : ω.String → List ℕ = λ str ⇒
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let words = string.split char.ws? str in
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list.map String ℕ string.to-ℕ-or-0 words;
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split-file : ω.String → [ω. List (List ℕ)] = λ str ⇒
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[list.mapω String (List ℕ) split-numbers (split-lines str)] in
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io.mapω String [ω.List (List ℕ)] split-file (io.read-fileω path)
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def FILE : String = "in/day9"
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-- #[main]
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def doot =
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io.bindω (List (List ℕ)) True
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(read-file FILE)
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(λ lists ⇒ io.dump (List (List ℕ)) lists)
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#[main]
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def part1 =
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io.bindω (List (List ℕ)) True
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(read-file FILE)
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(λ lists ⇒ io.dump ℕ (list.sum (list.mapω (List ℕ) ℕ next-entry lists)))
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