83. Remove Duplicates from Sorted List

Question

Total Accepted: 102841 Total Submissions: 284006 Difficulty: Easy

 

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.

 

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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 || head->next == NULL) return head;13         ListNode* p1 = head->next;14         ListNode* p2 = head;15         while(p1 != NULL){16             if(p1->val == p2->val){17                 p1 = p1->next;18             }19             else{20                 p2->next = p1;21                 p2 = p2->next;22                 p2->val = p1->val;23                 p1 = p1->next;24             }25         }26         p2->next = NULL;27         return head;28     }29 };