image.png
要注意的问题：因为可能head也需要被删掉，所以需要一个dummy节点。
/**
* 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) {
if(head == NULL){
return NULL;
}
ListNode *dummy = new ListNode(0);
ListNode *cur = head;
ListNode *prev = dummy;
int flag = 0;
while(cur){
if(cur->next && cur->val == cur->next->val){
cur->next = cur->next->next;
flag = 1;
}
if(flag){
prev->next = cur->next;
cur = prev->next;
flag = 0;
cout<<prev->val<<endl;
}
else{
prev = cur;
cur = cur->next;
}
}
return dummy->next;
}
};
