PAT 02-线性结构3 Reversing Linked List 【JAVA实现】

一、题目内容为：
Given a constant K and a singly linked list L, you are supposed to reverse the links of every K elements on L. For example, given L being 1→2→3→4→5→6, if K = 3, then you must output 3→2→1→6→5→4; if K = 4, you must output 4→3→2→1→5→6.Given a constant K and a singly linked