题目如下：
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.
Input Specification:
Each input file contains one test case. For each case, the first line contains the address of the first node, a positive N (<= 105) which is the total number of nodes, and a positive K (<=N) which is the length of the sublist to be reversed. The address of a node is a 5-digit nonnegative integer, and NULL is represented by -1.
Then N lines follow, each describes a node in the format:
Address Data Next
where Address is the position of the node, Data is an integer, and Next is the position of the next node.
Output Specification:
For each case, output the resulting ordered linked list. Each node occupies a line, and is printed in the same format as in the input.
Sample Input:00100 6 4 00000 4 99999 00100 1 12309 68237 6 -1 33218 3 00000 99999 5 68237 12309 2 33218Sample Output:
00000 4 33218 33218 3 12309 12309 2 00100 00100 1 99999 99999 5 68237 68237 6 -1
这是一道著名坑题，如果真的用单向链表来做，实在是太变态了，下面给出一种利用map和vector完成的简单方法。
这道题最大的坑在于有无效结点，也就是说除了从头结点走到-1的所有结点外，还有其他子链表，排除的方法很简单，只要从头到尾走一遍记录下来，其他的全部扔掉。
要解决这个问题，需要考虑以下几个方面：
①如何根据题目输入存储结点？
采用结构体数组，规模为10万，下标即为自己的地址，结构体内存储编号和下一个地址。
②如何进行反转？
只用vector记录有效结点的编号，同时在记录时用map记录编号到地址的对应关系。
只反转vector中的编号。
③如何连接地址输出？
通过反转后的vector，结合map查询地址，实现地址连接。
一定要注意处理K=N和N=1的情况，注意地址的前导0，-1不能有前导0。
代码如下：
#include
#include
#include