lean4-htt/tests/bench/unionfind.lean
Kim Morrison 3a408e0e54
feat: change Array.get to take a Nat and a proof (#6032)
This PR changes the signature of `Array.get` to take a Nat and a proof,
rather than a `Fin`, for consistency with the rest of the (planned)
Array API. Note that because of bootstrapping issues we can't provide
`get_elem_tactic` as an autoparameter for the proof. As users will
mostly use the `xs[i]` notation provided by `GetElem`, this hopefully
isn't a problem.

We may restore `Fin` based versions, either here or downstream, as
needed, but they won't be the "main" functions.

---------

Co-authored-by: David Thrane Christiansen <david@davidchristiansen.dk>
2024-11-12 03:30:46 +00:00

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def StateT' (m : Type → Type) (σ : Type) (α : Type) := σ → m (α × σ)
namespace StateT'
variable {m : Type → Type} [Monad m] {σ : Type} {α β : Type}
@[inline] protected def pure (a : α) : StateT' m σ α := fun s => pure (a, s)
@[inline] protected def bind (x : StateT' m σ α) (f : α → StateT' m σ β) : StateT' m σ β := fun s => do let (a, s') ← x s; f a s'
@[inline] def read : StateT' m σ σ := fun s => pure (s, s)
@[inline] def write (s' : σ) : StateT' m σ Unit := fun s => pure ((), s')
@[inline] def updt (f : σσ) : StateT' m σ Unit := fun s => pure ((), f s)
instance : Monad (StateT' m σ) :=
{pure := @StateT'.pure _ _ _, bind := @StateT'.bind _ _ _}
end StateT'
def ExceptT' (m : Type → Type) (ε : Type) (α : Type) := m (Except ε α)
namespace ExceptT'
variable {m : Type → Type} [Monad m] {ε : Type} {α β : Type}
@[inline] protected def pure (a : α) : ExceptT' m ε α := (pure (Except.ok a) : m (Except ε α))
@[inline] protected def bind (x : ExceptT' m ε α) (f : α → ExceptT' m ε β) : ExceptT' m ε β :=
(do { let v ← x; match v with
| Except.error e => pure (Except.error e)
| Except.ok a => f a } : m (Except ε β))
@[inline] def error (e : ε) : ExceptT' m ε α := (pure (Except.error e) : m (Except ε α))
@[inline] def lift (x : m α) : ExceptT' m ε α := (do {let a ← x; pure (Except.ok a) } : m (Except ε α))
instance : Monad (ExceptT' m ε) :=
{pure := @ExceptT'.pure _ _ _, bind := @ExceptT'.bind _ _ _}
end ExceptT'
abbrev Node := Nat
structure nodeData :=
(find : Node) (rank : Nat := 0)
abbrev ufData := Array nodeData
abbrev M (α : Type) := ExceptT' (StateT' Id ufData) String α
@[inline] def read : M ufData := ExceptT'.lift StateT'.read
@[inline] def write (s : ufData) : M Unit := ExceptT'.lift (StateT'.write s)
@[inline] def updt (f : ufData → ufData) : M Unit := ExceptT'.lift (StateT'.updt f)
@[inline] def error {α : Type} (e : String) : M α := ExceptT'.error e
def run {α : Type} (x : M α) (s : ufData := ∅) : Except String α × ufData :=
x s
def capacity : M Nat :=
do let d ← read; pure d.size
def findEntryAux : Nat → Node → M nodeData
| 0, n => error "out of fuel"
| i+1, n =>
do let s ← read;
if h : n < s.size then
do { let e := s[n];
if e.find = n then pure e
else do let e₁ ← findEntryAux i e.find;
updt (fun s => s.set! n e₁);
pure e₁ }
else error "invalid Node"
def findEntry (n : Node) : M nodeData :=
do let c ← capacity;
findEntryAux c n
def find (n : Node) : M Node :=
do let e ← findEntry n; pure e.find
def mk : M Node :=
do let n ← capacity;
updt $ fun s => s.push {find := n, rank := 1};
pure n
def union (n₁ n₂ : Node) : M Unit :=
do let r₁ ← findEntry n₁;
let r₂ ← findEntry n₂;
if r₁.find = r₂.find then pure ()
else updt $ fun s =>
if r₁.rank < r₂.rank then s.set! r₁.find { find := r₂.find }
else if r₁.rank = r₂.rank then
let s₁ := s.set! r₁.find { find := r₂.find };
s₁.set! r₂.find { r₂ with rank := r₂.rank + 1 }
else s.set! r₂.find { find := r₁.find }
def mkNodes : Nat → M Unit
| 0 => pure ()
| n+1 => do _ ← mk; mkNodes n
def checkEq (n₁ n₂ : Node) : M Unit :=
do let r₁ ← find n₁; let r₂ ← find n₂;
unless (r₁ = r₂) do error "nodes are not equal"
def mergePackAux : Nat → Nat → Nat → M Unit
| 0, _, _ => pure ()
| i+1, n, d => do
let c ← capacity;
if (n+d) < c
then union n (n+d) *> mergePackAux i (n+1) d
else pure ()
def mergePack (d : Nat) : M Unit :=
do let c ← capacity; mergePackAux c 0 d
def numEqsAux : Nat → Node → Nat → M Nat
| 0, _, r => pure r
| i+1, n, r =>
do let c ← capacity;
if n < c
then do { let n₁ ← find n; numEqsAux i (n+1) (if n = n₁ then r else r+1) }
else pure r
def numEqs : M Nat :=
do let c ← capacity;
numEqsAux c 0 0
def test (n : Nat) : M Nat :=
if n < 2 then error "input must be greater than 1"
else do
mkNodes n;
mergePack 50000;
mergePack 10000;
mergePack 5000;
mergePack 1000;
numEqs
def main (xs : List String) : IO UInt32 :=
let n := xs.head!.toNat!;
match run (test n) with
| (Except.ok v, s) => IO.println ("ok " ++ toString v) *> pure 0
| (Except.error e, s) => IO.println ("Error : " ++ e) *> pure 1