力扣82. 删除排序链表中的重复元素 II

 

单链表真的遭罪，不过有一个技巧，就是创建一个head，这样便于处理首元素就需要删除的情况。

题目：【https://leetcode.cn/problems/remove-duplicates-from-sorted-list-ii/?envType=study-plan-v2&envId=top-interview-150】

 

 1 /**
 2  * Definition for singly-linked list.
 3  * struct ListNode {
 4  *     int val;
 5  *     ListNode *next;
 6  *     ListNode() : val(0), next(nullptr) {}
 7  *     ListNode(int x) : val(x), next(nullptr) {}
 8  *     ListNode(int x, ListNode *next) : val(x), next(next) {}
 9  * };
10  */
11 class Solution {
12 public:
13     ListNode* deleteDuplicates(ListNode* head) {
14         ListNode* thead = new ListNode(-10000, head);
15         ListNode* t = thead;
16         ListNode* s = thead;
17         ListNode* f = s->next;
18         bool flag = false;
19 
20         while (f) {
21             if (s->val != f->val) {
22                 if (flag) {
23                     flag = false;
24                     removeRange(t, f);
25                     s = t;//->next; if (NULL != s) break;
26                     f = s->next;
27                     continue;
28                 }
29                 t = s;
30                 s = s->next;
31                 f = f->next;
32             } else {
33                 flag = true;
34                 f = f->next;
35             }
36         }
37 
38         if (flag)
39             removeRange(t, NULL);
40         
41         head = thead->next;
42         delete thead;
43         return head;
44     }
45 
46 private:
47     void removeRange(ListNode* start, ListNode* end)
48     {
49         ListNode* t;
50         ListNode* d = start->next;
51 
52         while (end != d) {
53             t = d->next;
54             delete d;
55             d = t;
56         }
57 
58         start->next = end;
59     }
60 };

 

posted @ 2025-05-09 14:34  J&YANG  阅读(9)  评论(0)    收藏  举报