C++ 代码

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution {
public:
    ListNode* deleteDuplication(ListNode* head) {
        if(!head||!head->next){
            return head;
        }
        ListNode* dummy=new ListNode(0);
        dummy->next=head;
        ListNode*pre=dummy;
        ListNode*cur=head;
        int num=0;
        while(cur){
            num=0;
            //1-1-1-1-2
            while(cur->next&&cur->next->val==cur->val){
                cur=cur->next;
                num++;
            }
            if(num>0){
                //说明有重复的
                pre->next=cur->next;
            }else{
                //等于0，说明没有重复的
                pre=cur;
            }
            cur=cur->next;
        }
        return dummy->next;
    }
};