Problem:

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

For example,

Given 1->1->2, return 1->2.

Given 1->1->2->3->3, return 1->2->3.

Summary:

删除链表中的重复元素。

Analysis:

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) {13             return head;14         }15         16         ListNode *tmp = head;17         while (tmp->next != NULL) {18             ListNode *p = tmp->next;19             if (tmp->val == p->val) {20                 tmp->next = p->next;21                 delete p;22             }23             else {24                 tmp = tmp->next;25             }26         }27         28         return head;29     }30 };