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import Lean
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open Lean Meta
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/-! ## Graph -/
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variable [inst : BEq α] [inst : Hashable α]
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structure Graph (α β : Type) [inst : BEq α] [inst : Hashable α] where
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nodes: HashMap α β := {}
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edges: Array (α × α) := {}
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deriving Inhabited
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instance [ToJson β] : ToJson (Graph Name β) := {
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toJson := fun graph => Json.mkObj [
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("nodes", Json.mkObj (graph.nodes.toList.map fun (a,b) => (a.toString, toJson b))),
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("edges", toJson graph.edges)
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]
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}
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instance : EmptyCollection (Graph α β) := ⟨default⟩
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def Graph.insertNode (g : Graph α β) (a : α) (b : β) :=
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{g with nodes := g.nodes.insert a b}
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partial def Graph.predecessors (g : Graph α β) (x : α) (acc : HashSet α := {}) : HashSet α := Id.run do
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let mut res := acc
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let directPredecessors := (g.edges.filter (·.2 == x)).map (·.1)
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for y in directPredecessors do
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if ¬ res.contains y then
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res := res.insert y
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res := g.predecessors y res
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return res
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