剑指offer——20删除链表中重复的结点

 1 class Solution {
 2 public:
 3     ListNode* deleteDuplication(ListNode* pHead)    {
 4         if (pHead == nullptr || pHead->next == nullptr)return pHead;
 5         ListNode *newHead = new ListNode(0);
 6         newHead->next = pHead;
 7         ListNode *pre = newHead, *p = newHead->next;
 8         int sameNum = 0;
 9         while (p!= nullptr && p->next != nullptr)
10         {
11             if (p->val == p->next->val)
12             {
13                 sameNum = p->val;
14                 while (pre->next != nullptr && pre->next->val == sameNum)
15                     pre->next = pre->next->next;
16                 p = pre->next;
17             }
18             else
19             {
20                 pre = p;
21                 p = p->next;
22             }
23         }
24         return newHead->next;
25     }
26 };