LeetCode【83】Remove Duplicates from Sorted List

Given a sorted linked list, delete all duplicates such that each element appear only once.

For example,
Given 1->1->2, return 1->2.
Given 1->1->2->3->3, return 1->2->3.

简单的题目，直接上AC代码：

    ListNode* deleteDuplicates(ListNode* head) {
        if(!head)
            return NULL;
        ListNode*fir = head;
        ListNode*sec = fir->next;
        while(sec)
        {
            if(fir->val == sec->val)
            {
                sec= sec->next;
            }
            else
            {
                fir->next = sec;
                fir = sec;
                sec= sec->next;
            }
        }
        fir->next = sec;
        return head;
    }