Leetcode | | 83. Remove Duplicates from Sorted List

Problem:

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

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

Hide TagsLinked ListTest instructions: Removes duplicate elements from an already ordered single-linked list, leaving only one

Thinking:

(1) This problem is a simplified version of the previous question, the previous question is to duplicate the elements of a non-stay delete: http://blog.csdn.net/hustyangju/article/details/45028247

(2) Double pointer traversal, time complexity O (N), single commit AC

Code

/** * Definition for singly-linked list. * struct ListNode {*     int val; *     ListNode *next; *     listnode (int x): Val (x), Next (NULL) {} *}; */class Soluti On {public:    listnode *deleteduplicates (ListNode *head) {        if (Head==null | | head->next==null)              return Head;          ListNode *p=head;//left pointer          listnode *q=p;//Right pointer while          (p!=null)          {              q=p->next;//Right pointer initialize              if (q== NULL)                  return head;              if (p->val!=q->val)//unequal, while advancing              {                  p=p->next;                  q=q->next;              }              else/equal, right pointer forward              {while                  (q!=null && q->val==p->val)                  {                      q=q->next;                  }                  p->next=q;  Delete duplicate element                  p=q;        Update left Pointer              }          }          return head;}              ;

Leetcode | | 83. Remove Duplicates from Sorted List