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(head==NULL)
return NULL;
if(head->next==NULL)
return head;
ListNode* p=head;
int key=p->val;
p=p->next;
ListNode* q=head;
while(p)
{
if(p->val==key)
{
ListNode* toBeDeleted=p;
q->next=toBeDeleted->next;
p=q->next;
delete toBeDeleted;
toBeDeleted=NULL;
}
else
{
key=p->val;
p=p->next;
q=q->next;
}
}
return head;
}
};