Pre-order traversal of the following binary tree:对以下二叉树进行先序遍历:
When you have just finished accessing node d (Implementation 2), the elements in the stack from the top of the stack to the bottom of the stack are:刚访问完节点d时(迭代实现2)栈中的元素从栈顶到栈底依次为:
Ae
Bg,f
Cf,g
Df