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Optimizing findFirstDfs to a tail recursive function

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This commit is contained in:
Chris Stewart 2016-02-20 12:44:46 -06:00
parent ad7383bac5
commit a94fe6393f
1 changed files with 12 additions and 9 deletions
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21
src/main/scala/org/scalacoin/util/BinaryTree.scala
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@ -51,15 +51,18 @@ trait BinaryTree[+T] {
* @return
*/
def findFirstDFS[T](t : T)(f : T => Boolean = (x : T) => x == t)(implicit tree : BinaryTree[T] = this) : Option[BinaryTree[T]] = {
//TODO: Optimize this to be tail recursive
if (tree.value.isDefined && f(tree.value.get)) Some(tree)
else {
val leftTreeResult : Option[BinaryTree[T]] = if (tree.left.isDefined) findFirstDFS(t)(f)(tree.left.get) else None
if (leftTreeResult.isDefined) leftTreeResult
else if (tree.right.isDefined) findFirstDFS(t)(f)(tree.right.get)
else None
@tailrec
def loop(subTree : BinaryTree[T], remainder : List[BinaryTree[T]]) : Option[BinaryTree[T]] = {
subTree match {
case Empty => if (remainder.isEmpty) None else loop(remainder.head, remainder.tail)
case Leaf(x) => if (f(x)) Some(Leaf(x)) else if (remainder.isEmpty) None else loop(remainder.head, remainder.tail)
case Node(v, l, r) =>
if (f(v)) Some(Node(v,l,r))
else loop(l, r :: remainder)
}
}
loop(tree,List())
}
/**
@ -94,7 +97,7 @@ trait BinaryTree[+T] {
* if it cannot insert it because the branches are not empty
* it throws a runtime exception
* @param subTree
* @param tree
* @param parentTree
* @tparam T
* @return
*/
@ -108,6 +111,7 @@ trait BinaryTree[+T] {
}
def remove[T](subTree : BinaryTree[T])(parentTree : BinaryTree[T] = this) : BinaryTree[T] = {
//TODO: Optimize into a tail recursive function
parentTree match {
@ -128,7 +132,6 @@ trait BinaryTree[+T] {
* @return
*/
def replace[T](originalTree : BinaryTree[T], replacement : BinaryTree[T])(implicit parentTree : BinaryTree[T] = this) : BinaryTree[T] = {
parentTree match {
case Empty => Empty
case l : Leaf[T] => if (l == originalTree) replacement else l