/**
 * struct ListNode {
 *	int val;
 *	struct ListNode *next;
 * };
 */

class Solution {
public:
    /**
     * 
     * @param head ListNode类 
     * @return ListNode类
     */
    ListNode* deleteDuplicates(ListNode* head) {
        if (!head) {
            return head;
        }
        ListNode *now = head;
        while (now) {
            ListNode *tmp = now->next;
            while (tmp && (tmp->val == now->val)) {
                tmp = tmp->next;
            }
            now->next = tmp;
            now = tmp;
        }
        return head;
    }
};

思路:模拟。因为是有序链表,所以重复元素都在一起,遍历链表,对每个元素,往后遍历删除重复的即可。