基本的链表操作，只需一次遍历即可

1     ListNode *deleteDuplicates(ListNode *head) { 2         if(!head) 3             return NULL; 4         ListNode *cur, *next; 5         cur = head; 6         while(cur){ 7             next = cur->next; 8             while(next){ 9                 if(next->val != cur->val)10                     break;11                 next = next->next;12             }13             cur->next = next;14             cur = cur->next;15         }16         return head;17     }