[Linked List]Remove Duplicates from Sorted List II

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution {
public:
    ListNode* deleteDuplicates(ListNode* head) {
        ListNode* delete_from=NULL,*delete_to=NULL;
        ListNode* pre =NULL,*cur=head,*cur_next=NULL;
        while(cur){
            cur_next = cur->next;
            
            /* 找值相同的链串 */
            bool has_found = false;
            while(cur_next && cur_next->val == cur->val){
                cur_next = cur_next->next;
                has_found = true;
            }
            
            /*如果找到了连续的重复元素，则删除重复值的串链，如果没找到更新前驱结点*/
            if(has_found){
                delete_from = cur;
                delete_to = cur_next;
                while(delete_from != delete_to){
                    ListNode* tmp = delete_from->next;
                    delete(delete_from);
                    delete_from = tmp;
                }    
                pre ? pre->next=cur_next : head = cur_next;
            }else{
                pre = cur;
            }

            cur = cur_next;
        }
        return head;
    }
};