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:

#include <cstdio>
using namespace std;
struct node
{
    int nValue;
    struct node* next;
};
node* reserveNodeList(node* head)
{
    if (head == NULL) return NULL;
    node* pRes = head;
    node* pNext = head->next;
    head->next = NULL;
    while (pNext != NULL)
    {
        head = pNext->next;
        pNext->next = pRes;
        pRes = pNext;
        pNext = head;
    }
    head = pRes;
    return head;
}
int main()
{
    int n;
    scanf("%d", &n);
    if (n == -1) return 0;
    node* head = new node;
    head->nValue = n;
    head->next = NULL;
    node* p = head;
    while (scanf("%d", &n), n != -1)
    {
        node* pCurrent = new node;
        p->next = pCurrent;
        pCurrent->nValue = n;
        pCurrent->next = NULL;
        p = p->next;
    }
    head = reserveNodeList(head);
    while (head != NULL)
    {
        printf("%d
", head->nValue);
        head = head->next;
    }
    return 0;
}