082 - Remove Duplicates from Sorted List II

Remove Duplicates from Sorted List II

Given a sorted linked list, delete all nodes that have duplicate numbers, leaving only distinct numbers from the original list.
For example,
Given 1->2->3->3->4->4->5, return 1->2->5.
Given 1->1->1->2->3, return 2->3.
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Linked List

没啥可说的，用prev记住前一个，看看是否有重复的，
如果没有，prev 和 p 同步向前平移。
如果有，用p跳过所有相等的，pre->next = p->next；p = p->next;

/**
* 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(0);
        dummy.next = head;
        ListNode* p = head;
        ListNode* prev = &dummy;
       
        if(head && head->next)
        {
            while(p)
            {
                while((p->next)&&(p->val == p->next->val))
                    p = p->next;
                if(p == prev->next)  //no duplicated nodes
                    prev = p;
                else                 //duplicated nodes skipped.
                    prev->next = p->next;
                p = p->next;
            }
        }
        return dummy.next;
    }
};
8 ms.