Created
April 15, 2020 02:58
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def preOrderR[T,S](tree: Tree[T], f: T => S): Queue[S] = { | |
def loop(stack: List[Tree[T]], output: Queue[S]): Queue[S] = stack match { | |
case Nil => output | |
case Tree(v,c)::ts => loop(c:::ts,output.enqueue(f(v))) | |
} | |
loop(tree::Nil, Queue.empty) | |
} | |
def postOrderR[T,S](tree: Tree[T], f: T => S): Queue[S] = { | |
def loop(stack: List[Tree[T]], output: Queue[S]): Queue[S] = stack match { | |
case Nil => output | |
case Tree(v,Nil)::ts => loop(ts,output.enqueue(f(v))) | |
case Tree(v,c::cs)::ts => loop(c::Tree(v,cs)::ts, output) | |
} | |
loop(tree::Nil,Queue.empty) | |
} |
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