开始刷leetcode day9：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 pre = head;
        ListNode node = head.next;
        while(node != null)
        {
            if( pre.val != node.val)
            {
                pre = node;
                node = node.next;
            }else
            {
                pre.next = node.next;
                node = node.next;
            }
        }
        return head;
    }
}