83. Remove Duplicates from Sorted List

Posted 2020-10-11 lvbbg

83. Remove Duplicates from Sorted List

---

Given a sorted linked list, delete all duplicates such that each element appear only once.

For example,
Given 1->1->2, return 1->2.
Given 1->1->2->3->3, return 1->2->3.

 

pre指针在后

cur向前扫，扫到不重复的就让节点和pre指向的ListNode连在一起，扫到重复的就继续扫，直到不重复的时候，再和pre指向的ListNode连接

效果是：重新连了一遍，扔掉了重复的节点

 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 
10 class Solution {
11 public:
12     ListNode *deleteDuplicates(ListNode *head) {
13         if(head==NULL||head->next==NULL)
14             return head;
15         
16         ListNode* pre=head;
17         ListNode* cur=head->next;
18         
19         while(cur!=NULL){
20             if(cur->val==pre->val) {
21                 cur=cur->next;
22             }else{
23                 pre->next=cur;
24                 pre=cur;
25                 cur=cur->next;
26             }
27         }
28         pre->next=NULL;
29         return head;
30     }
31 };