Given a sorted linked list, delete all duplicates such that each element appear only once.
For example,
Given 1->1->2
, return 1->2
.
Given 1->1->2->3->3
, return 1->2->3
.
/**
* 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(NULL == head)
return NULL;
ListNode *p = head;
ListNode *q = head->next;
while(q)
{
if(p->val == q->val)
{
ListNode *t = q;
p->next = q->next;
q = p->next;
delete t;
}
else
{
p = q;
q = q->next;
}
}
return head;
}
};
不能省略
- if(NULL == head)
- return NULL;