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.

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     struct ListNode *next;
 * };
 */
struct ListNode* deleteDuplicates(struct ListNode* head) {
    struct ListNode* cur = head, *tmp = head;
    while(cur != NULL && cur->next != NULL)    //这里，连在一起，如果cur=null，则后面的就不会运行了
    {
        tmp = cur->next;
        if(cur->val == tmp->val)
        {
            cur->next = tmp->next;
            free(tmp);
        }
        else
            cur = cur->next;
    }
    return head;
}