题解 | #删除有序链表中重复的元素-II#

/**
 * struct ListNode {
 *	int val;
 *	struct ListNode *next;
 *	ListNode(int x) : val(x), next(nullptr) {}
 * };
 */
class Solution {
public:
    ListNode* deleteDuplicates(ListNode* head) {
        auto slow = head, fast = head;
        ListNode* newlist = nullptr;
        ListNode* curr = nullptr;
        while (fast) {
            int cnt = 0;
            while (fast && fast->val == slow->val) {
                cnt++;
                fast = fast->next;
            }
            cout << cnt << endl;
            if (cnt == 1) {
                if (newlist == nullptr) {
                    newlist = slow;
                    curr = slow;
                } else {
                    curr->next = slow;
                    curr = curr->next;
                }
            }
            slow->next = fast;
            slow = slow->next;
        }
        if (curr == nullptr) return nullptr;
        else {
            curr->next = nullptr;
            return newlist;
        }
    }
};