3f548edcd7
When updating Std, be careful that not every lemma has been upstreamed, so we need to be careful to only delete things that have already been declared.
25 lines
871 B
Text
25 lines
871 B
Text
-- Extracted from Mathlib.Data.UnionFind.
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-- This file was failing in Mathlib during development of #3124.
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section Mathlib.Data.UnionFind
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structure UFNode (α : Type _) where
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parent : Nat
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value : α
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rank : Nat
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structure UnionFind (α) where
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arr : Array (UFNode α)
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-- The `PANIC` can be avoided by turning `simprocs` off:
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-- set_option simprocs false
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def rankMaxAux (self : UnionFind α) : ∀ (i : Nat),
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{k : Nat // ∀ j, j < i → ∀ h, (self.arr.get ⟨j, h⟩).rank ≤ k}
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| 0 => ⟨0, fun j hj => nomatch hj⟩
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| i+1 => by
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let ⟨k, H⟩ := rankMaxAux self i
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refine ⟨max k (if h : _ then (self.arr.get ⟨i, h⟩).rank else 0), fun j hj h ↦ ?_⟩
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match j, Nat.lt_or_eq_of_le (Nat.le_of_lt_succ hj) with
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| j, Or.inl hj => exact Nat.le_trans (H _ hj h) (Nat.le_max_left _ _)
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| _, Or.inr rfl => simp [h, Nat.le_max_right]
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