[LeetCode]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.

/** * Definition for singly-linked list. * public class ListNode { *     int val; *     ListNode next; *     ListNode(int x) { *         val = x; *         next = null; *     } * } */public class Solution {    public ListNode deleteDuplicates(ListNode head) {    ListNode res = new ListNode(0);    res.next = head;    ListNode ln = head;    ListNode li = res;    while(ln!=null){    boolean dup = false;    while(ln.next!=null&&ln.val == ln.next.val){    ln = ln.next;    dup = true;    }    if(dup){    li.next = ln;        }else{    li = li.next;    }    ln = li.next;    }    return res.next;    }}