删除排序链表中的重复元素

ListNode *deleteDuplicates(ListNode *head) {
    if (head == nullptr) return head;
    ListNode *cur = head;
    while (cur->next != nullptr) {
        if (cur->val == cur->next->val) {
            // cur->next = cur->next->next;
            // 内存回收版本
            ListNode *tmp = cur->next;
            cur->next = cur->next->next;
            delete tmp;
        } else {
            cur = cur->next;
        }
    }
    return head;
}