LeetCode 83. 删除排序链表中的重复元素

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution {
public:
    ListNode* deleteDuplicates(ListNode* head) {
        auto l=new ListNode(-1);
        l->next=head;
        if(!head)return NULL;
        auto p=l->next;
        while(p->next){
            if(p->val==p->next->val)
                p->next=p->next->next;
            else
                p=p->next;
        }
        return l->next;
    }
};