82.cpp

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode() : val(0), next(nullptr) {}
 *     ListNode(int x) : val(x), next(nullptr) {}
 *     ListNode(int x, ListNode *next) : val(x), next(next) {}
 * };
 */
class Solution {
public:
    ListNode* deleteDuplicates(ListNode* head) {
        ListNode h(0, head);
        for (auto p = &h; p->next;) {
            if (auto temp = p->next->next;
                temp != nullptr && p->next->val == temp->val) {
                while (temp && p->next->val == temp->val)
                    temp = temp->next;
                p->next = temp;
            } else {
                p = p->next;
            }
        }
        return h.next;
    }
};