LintCode-剑指Offer-(112)删除排序链表中的重复元素

class Solution {
public:
/**
* @param head: The first node of linked list.
* @return: head node
*/
ListNode *deleteDuplicates(ListNode *head) {
// write your code here
ListNode* tmp = head;
ListNode* pre = NULL;
while (tmp!=NULL){
pre = tmp;
tmp = tmp->next;
while (tmp!=NULL&&tmp->val==pre->val){
pre->next = tmp->next;
delete tmp;
tmp = pre->next;
}
}
return head;
}
};