Remove Duplicates from Sorted List II

描述
Given a sorted linked list, delete all nodes that have duplicate numbers, leaving only distinct numbers
from the original list.
For example,
Given 1->2->3->3->4->4->5, return 1->2->5.
Given 1->1->1->2->3, return 2->3.
中文：删除掉所有含有重复元素的结点。
分析：如果此元素与下一个元素是重复的，则删除此元素。
并且记录该元素是否重复。
根据上面的重复标志位，决定最后是否删除该元素。

class Solution {public:     ListNode *deleteDuplicates(ListNode *head) {     if (head == nullptr) return head;     ListNode dummy(INT_MIN); //定义一个头结点     dummy.next = head;//让头结点指向链表第一个节点     ListNode *prev = &dummy, *cur = head;//定义两个指针结点     while (cur != nullptr) {            bool duplicated = false;            while (cur->next != nullptr && cur->val == cur->next->val) {                  duplicated = true;                  ListNode *temp = cur;                  cur = cur->next;                  delete temp;            }          if (duplicated) { // 根据重复位的标志，判断是否删除重复的最后一个元素                 ListNode *temp = cur;                 cur = cur->next;                 delete temp;                 continue;           }         prev->next = cur;         prev = prev->next;         cur = cur->next;   }   prev->next = cur;   return dummy.next;}};