题解 | #删除链表中重复的结点#

测试用例：{1,1,1,1,1,2,2,3,3,4,4,4,5,6,7,7,8,33,33,40}

/*
struct ListNode {
    int val;
    struct ListNode *next;
    ListNode(int x) :
        val(x), next(NULL) {
    }
};
*/
class Solution {
public:
    ListNode* deleteDuplication(ListNode* pHead) {
        if(!pHead)  return pHead;
        ListNode* pnode=pHead;
        ListNode* node=pHead->next;
        int flag=0;
        while(pnode)
        {
            while(node&&pnode->val==node->val)
            {
                flag=1;
                node = node->next;
            }
            if(flag)
            {
                pnode=node;
                if(!pnode)  return nullptr;
                node=node->next;
                flag=0;
            }
            else {
                break;
            }
        }
        pHead=pnode;
        unordered_map<int,int> mp;
        mp[pnode->val] = 1;
        
        while(node)
        {
            mp[node->val]+=1;
            if(mp[node->val]==1)
            {
                if(node->next==nullptr||node->val!=node->next->val)
                {
                    pnode->next=node;
                    pnode = node;
                }
            }
            node = node->next;
        }
        pnode->next=node;
        return pHead;
    }
};