83. Remove Duplicates from Sorted List


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

.

java：

/**
* Definition for singly-linked list.
* public class ListNode {
*     int val;
*     ListNode next;
*     ListNode(int x) { val = x; }
* }
*/
public class Solution {
public ListNode deleteDuplicates(ListNode head) {
if(head==null||head.next==null) return head;
ListNode a=head;
ListNode b=head.next;
while(b!=null)
{
if(a.val==b.val)
{
a.next=b.next;
b=b.next;
}
else
{
a=b;
b=b.next;
}
}
return head;

}
}

c++：

/**
* 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 head;
ListNode* p=head;
ListNode* q=head->next;
while(q!=NULL)
{
if(q->val==p->val)
{
p->next = q->next;
}
else
{
p=q;
}
q = q->next;

}
return head;

}
};