面试题5：从尾到头打印链表

题目链接：http://ac.jobdu.com/problem.php?pid=1511

思路：修改链表的指向。

使用三个指针head pRes pNext

保存pRes = head
保存head = pNext->next
修改pNext->next = pRes
更新pRes = pNext
更新pNext = head

code:

 1 #include <cstdio>

 2 using namespace std;

 3 struct node

 4 {

 5     int nValue;

 6     struct node* next;

 7 };

 8 node* reserveNodeList(node* head)

 9 {

10     if (head == NULL) return NULL;

11     node* pRes = head;

12     node* pNext = head->next;

13     head->next = NULL;

14     while (pNext != NULL)

15     {

16         head = pNext->next;

17         pNext->next = pRes;

18         pRes = pNext;

19         pNext = head;

20     }

21     head = pRes;

22     return head;

23 }

24 int main()

25 {

26     int n;

27     scanf("%d", &n);

28     if (n == -1) return 0;

29     node* head = new node;

30     head->nValue = n;

31     head->next = NULL;

32     node* p = head;

33     while (scanf("%d", &n), n != -1)

34     {

35         node* pCurrent = new node;

36         p->next = pCurrent;

37         pCurrent->nValue = n;

38         pCurrent->next = NULL;

39         p = p->next;

40     }

41     head = reserveNodeList(head);

42     while (head != NULL)

43     {

44         printf("%d\n", head->nValue);

45         head = head->next;

46     }

47     return 0;

48 }