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 *ans=new ListNode(0);
   ans->next=head;
   ListNode *answer=ans;
   while(ans->next){
	   int flag=0;
	   ListNode *cur=ans;
    while(ans->next->next && ans->next->next->val==ans->next->val){
	      flag=1;
		  ans=ans->next;
	 }
	if(flag){
	    cur->next=ans->next->next;
	    ans=cur;
	}
	
	else{
	ans=ans->next;
	}
	
   }
   return answer->next; 
    }
};

82. Remove Duplicates from Sorted List II

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.

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思路：遍历，找到连续相同的就跳过