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Complete binary tree Scala implementation
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sealed trait CompleteBinaryTree[A] { | |
def lookup(size: Int, index: Int): A = (this, index) match { | |
case (Leaf(x), 0) => x | |
case (Leaf(_), _) => throw new Exception("Index is not in list.") | |
case (Node(x, _, _), 0) => x | |
case (Node(x, l, _), i) if i <= size / 2 => l.lookup(size / 2, i - 1) | |
case (Node(x, _, r), i) if i > size / 2 => r.lookup(size / 2, i - 1 - size / 2) | |
} | |
def update(size: Int, index: Int, y: A): CompleteBinaryTree[A] = (this, index) match { | |
case (Leaf(_), 0) => Leaf(y) | |
case (Leaf(_), _) => throw new Exception("Index is not in list.") | |
case (Node(_, l, r), 0) => Node(y, l, r) | |
case (Node(x, l, r), i) if i <= size / 2 => Node(x, l.update(size / 2, i - 1, y), r) | |
case (Node(x, l, r), i) if i > size / 2 => Node(x, l, r.update(size / 2, i - 1 - size / 2, y)) | |
} | |
} | |
object CompleteBinaryTree { | |
def apply[A](xs: List[A]): CompleteBinaryTree[A] = { | |
def inner(xs: List[A], size: Int): CompleteBinaryTree[A] = size match { | |
case 1 => Leaf(xs.head) | |
case s if Math.pow(2, Math.floor(Math.log(s + 1)/ Math.log(2))).toInt == s + 1 => { | |
val t = xs.tail | |
val s_ = size / 2 | |
Node(xs.head, inner(t.take(s_), s_), inner(t.drop(s_), s_)) | |
} | |
case _ => throw new Exception("Size is not a skew binary.") | |
} | |
inner(xs, xs.length) | |
} | |
} | |
case class Leaf[A](value: A) extends CompleteBinaryTree[A] | |
case class Node[A](value: A, l: CompleteBinaryTree[A], r: CompleteBinaryTree[A]) extends CompleteBinaryTree[A] |
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