def getCharCode(tree: HuffmanCodingTree, code: List[Int]): (Char, List[Int]) = (tree, code) match {
    case (tr, x :: xs) if tr.chars.length == 1 => (tr.chars.head, xs)
    case (tr, x :: xs) if x == 0 => getCharCode(tr.asInstanceOf[HuffmanCodingTreeNonLeaf].leftChild, xs)
    case (tr, x :: xs) if x == 1 => getCharCode(tr.asInstanceOf[HuffmanCodingTreeNonLeaf].leftChild, xs)
  }