/**   * 尋找最遠的葉子節點   */  public void findFarestLeaf() {    List<Node> path = new ArrayList<Node>();    List<Node> longestPath = findLongestPath(root, path);    Node leaf = longestPath.get(longestPath.size() - 1);    System.out.println("最遠的葉子節點是<" + leaf.key + ", " + leaf.value + ">，到根節點的距離是："+(longestPath.size() - 1));  }  public List<Node> findLongestPath(Node x, List<Node> path) {    if (x == null)      return path;    // 每次遞歸必須新建list，要不然會導致遞歸分支都在同一個list上面做，實際是把所有結點都加入這個list了    List<Node> currPath = new ArrayList<Node>();    currPath.addAll(path);    currPath.add(x);    List<Node> leftPath = findLongestPath(x.left, currPath);    List<Node> rightPath = findLongestPath(x.right, currPath);    if (leftPath.size() > rightPath.size())      return leftPath;    else      return rightPath;  }