Remove Duplicates from Sorted List(链表)

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.
* public class ListNode {
*     int val;
*     ListNode next;
*     ListNode(int x) { val = x; }
* }
*/
public class Solution {
public ListNode deleteDuplicates(ListNode head) {
ListNode p=head;           //这样是跟着动的
while(p!=null){
while(p!=null && p.next!=null && p.val==p.next.val){
p.next=p.next.next;
}
p=p.next;
}
return head;
}
}