二叉搜索树的第K个结点

TreeNode KthNode(TreeNode pRoot, int k) {
            if (pRoot == null || k == 0)
                return null;
            Queue<TreeNode> queue = new LinkedList<>();
            midGet(pRoot, queue);
            int count=0;
            while (!queue.isEmpty()&&count!=k-1){
                count++;
                queue.poll();
            }
            if (queue.isEmpty()){
                return null;
            }
            return queue.poll();
        }

        private void midGet(TreeNode pRoot, Queue<TreeNode> queue) {
            if (pRoot == null) {
                return;
            }
            midGet(pRoot.left,queue);
            queue.offer(pRoot);
            midGet(pRoot.right,queue);
        }