树的遍历（非递归方式实现）：首先按中序方式建立树并输入节点信息，通过栈实现树的非递归方式的先序、中序和后序的遍历-Tree traversal (non-recursive way): First of all, by the way in order to establish the tree and enter the node information, the realization of the tree through the stack of the first non-recurs