83. Remove Duplicates from Sorted List

/*
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.
思路：
当一个值重复出现时，只保留第一次出现的。
*/

/**
* Definition for singly-linked list.
* struct ListNode {
*     int val;
*     struct ListNode *next;
* };
*/
struct ListNode* deleteDuplicates(struct ListNode* head){
if(!head || !head->next) return head;
struct ListNode *fast=head;
while(fast)
{
if(fast->next && fast->val==fast->next->val)
{
fast->next=fast->next->next;
}
else
fast=fast->next;

}
return head;
}