reverse list链表逆序

 1 ListNode* reverseList(ListNode* head){
 2     if (head==NULL || head->next==NULL) return head;
 3     ListNode *pre=head, *cur=pre->next, *post;
 4     pre->next = NULL;
 5     while (cur!=NULL){
 6         post = cur->next;
 7         cur->next = pre;
 8         pre = cur;
 9         cur = post;
10     }
11     return pre;
12 }