假设树上每个结点所含的数据元素为一个字母，并且以孩子-兄弟链表为树的存储结构，试写一个按凹入表方式打印一棵树的算法-Assuming the data elements contained in each node of the tree is a letter, and with children- brothers list is stored in the structure of the tree, try to write a print statement by way of a t