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.
思路：此题与上一题异曲同工，详细解法例如以下：
/**
* 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 first = new ListNode(0);
ListNode last = first; ListNode p = head; while(head != null){
while(head.next != null){//去除反复项
if(p.val == head.next.val){
head = head.next;
}else{
break;
}
}
last.next = p;//每项仅仅加入一个值
last = last.next;
p = head = head.next;
last.next = null;
}
return first.next;
}
}