83. Remove Duplicates from Sorted List

问题:

去除有序链表中重复的节点。

Example 1:
Input: head = [1,1,2]
Output: [1,2]

Example 2:
Input: head = [1,1,2,3,3]
Output: [1,2,3]
 
Constraints:
The number of nodes in the list is in the range [0, 300].
-100 <= Node.val <= 100
The list is guaranteed to be sorted in ascending order.

  

解法:slow-fast pointers(快慢指针法)

  • 0~i:满足题意的链表。
  • j:探索是否当前节点满足题意(非重复):nums[j]!=nums[i](最后一个满足元素)
    • 若满足:交换 j 和第一个不满足元素 i->next
    • swap(i->next, j)
    • i=i->next
  • 继续探索下一个 j=j->next

 

代码参考:

 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         if(!head) return head;
15         ListNode* i=head, *j=head->next;
16         while(j) {
17             if(i->val != j->val) {
18                 swap(i->next->val, j->val);
19                 i=i->next;
20             }
21             j=j->next;
22         }
23         i->next=nullptr;
24         return head;
25     }
26 };

 

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