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.

  public class ListNode {

      int val;

      ListNode next;

      ListNode(int x) {

          val = x;

          next = null;

      }

  }

题目很简单，判断是相等的就直接指向下一个即可

public ListNode deleteDuplicates(ListNode head) {if(head==null) return null;ListNode last=head;ListNode next=head.next;while(next!=null){if(next.val==last.val){last.next=next.next;next=next.next;}else {last=next;next=next.next;}}return head;}