题解 | #删除有序链表中重复的元素-II#

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

class Solution {
public:
    /**
     * 
     * @param head ListNode类 
     * @return ListNode类
     */
    ListNode* deleteDuplicates(ListNode* head) {
        ListNode *dummy = new ListNode(0);
        dummy->next = head;
        ListNode *bef = dummy;
        while (bef) {
            ListNode *now = bef->next;
            if (!now) {
                break;
            }
            int val = now->val;
            int cnt = 0;
            while (now && (now->val == val)) {
                ++cnt;
                now = now->next;
            }
            if (cnt > 1) {
                bef->next = now;
            } else {
                bef = bef->next;
            }
        }
        return dummy->next;
    }
};

思路：遍历。

记录重复的节点个数，如果大于1则删除所有节点。