https://leetcode.com/problems/remove-duplicates-from-sorted-list-ii/
题目:
Given a sorted linked list, delete all nodes that have duplicate numbers, leaving only distinct numbers from the original list.
For example,
Given 1->2->3->3->4->4->5
, return 1->2->5
.
Given 1->1->1->2->3
, return 2->3
.
思路:
需要两个指针,a用来纪录新链表,b用来遍历老链表,因为只有删除操作,需要一个flag标记ab段要不要删除。此外要注意头节点的处理。
AC代码:
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) 13 return NULL; 14 ListNode* newhead=new ListNode(0); // to handle head 15 newhead->next=head; 16 ListNode* a=newhead,*b=newhead->next; 17 int now=head->val; 18 bool occur_flag=false; 19 while(b->next!=NULL){ 20 if(b->next->val==now){ 21 occur_flag=true; 22 } 23 else{ 24 if(occur_flag==true){ 25 a->next=b->next; //delete duplicate numbers 26 b=a; //update pointers 27 } 28 else{ 29 a=b; 30 } 31 occur_flag=false; 32 now=b->next->val; 33 } 34 b=b->next; 35 } 36 if(occur_flag==true){ 37 a->next=b->next; //delete duplicate numbers 38 b=a; //update pointers 39 } 40 else{ 41 a=b; 42 } 43 return newhead->next; 44 } 45 };
时间: 2024-11-11 18:48:47