LeetCode 82. 删除排序链表中的重复元素 II（Remove Duplicates from Sorted List II）

 1 /**
 2  * Definition for singly-linked list.
 3  * struct ListNode {
 4  *     int val;
 5  *     ListNode *next;
 6  *     ListNode(int x) : val(x), next(NULL) {}
 7  * };
 8  */
 9 class Solution {
10 public:
11     ListNode* deleteDuplicates(ListNode* head) {
12         if(head == NULL) return NULL;
13         ListNode *left = head;
14         while(left && left->next && left->val == left->next->val){
15             int val = left->val;
16             while(left && left->val == val)
17                 left = left->next;
18         }
19         if(left == NULL) return NULL;
20         head = left;
21         ListNode *right;
22         while(left){
23             right = left->next;
24             while(right && right->next && right->val == right->next->val){
25                 int val = right->val;
26                 while(right && right->val == val)
27                     right = right->next;
28             }
29             left->next = right;
30             left = right;
31         }
32         return head;
33     }
34 };