LeetCode82 Remove Duplicates from Sorted List II

题目链接:

https://leetcode.com/problems/remove-duplicates-from-sorted-list-ii/

题目描述:

删除链表中相同的元素，与之前一道题有区别的是，链表中只要重复出现过该元素，全部删除，之前只是删除重复的内容。

分析:

写的时候头昏脑涨，马上又要考试了，分析先不写了，因为写的时候晕晕的，逻辑也没处理好，代码写的太挫。之后整理好思路再回来写。

代码:

class Solution {
public:
   ListNode* deleteDuplicates(ListNode* head) {
    if (head == NULL || head->next == NULL){
        return head;
    }
    ListNode* pHead = (ListNode*)malloc(sizeof(ListNode));
    pHead->next = head;
    ListNode* pre = pHead;
    ListNode* cur = pre->next;
    ListNode* cmp = cur;
    bool flag;
    while (cur != NULL){
        flag = true;
        if (cmp->val != cur->val){
            flag = false;
            pre->next = cur;
            cmp = cur;
        }
        else{
            if (cmp == cur){
                if (cur->next != NULL &&cmp->val != cur->next->val){
                    pre = cur;
                    cmp = cur->next;
                }
                else if (cur->next == NULL){
                    pre = cur;
                }
            }
            cur = cur->next;
        }
    }
    if (flag){
        pre->next = cur;
    }
    return pHead->next;
}
};