本程序是为了实现单向链表的就地逆置。主要功能：按照提示输入5个字母a－z，输出结果是这5个字母按照字母表的顺序的排序。-this program is to achieve a one-way linked list of locally inverse home. The main functions : following the prompts to import five letters a-z, this output is five letters of the alphabet, according to the order of ranking.