调试中...
行 1，列 1
["BSTIterator","next","next","prev","next","hasNext","next","next","next","hasNext","hasPrev","prev","prev"]
[[[7,3,15,null,null,9,20]],[null],[null],[null],[null],[null],[null],[null],[null],[null],[null],[null],[null]]
["BSTIterator","next","next","prev","next","hasNext","next","next","next","hasNext","hasPrev","prev","prev"]
[[[7,3,15,null,null,9,20]],[null],[null],[null],[null],[null],[null],[null],[null],[null],[null],[null],[null]]