题目

给定一个排序链表，删除所有含有重复数字的节点，只保留原始链表中 没有重复出现 的数字。

示例 1:

输入: 1->2->3->3->4->4->5
输出: 1->2->5
示例 2:

输入: 1->1->1->2->3
输出: 2->3

解析

哑节点避免开头的特殊情况

代码

/**
 * 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) {
        ListNode* dummy = new ListNode(0);
        dummy->next = head;
        ListNode* pre = dummy;
        ListNode* cur = pre->next;
        while (cur) {
            int num = 0;
            ListNode* p = cur;
            while (p && p->val == cur->val) {
                ++num;
                p = p->next;
            }
            if (num > 1) {
                pre->next = p;
            } else {
                pre = cur;
            }
            cur = p;
        }
        ListNode* retNode = dummy->next;
        delete dummy;
        return retNode;
    }
};