Given a sorted linked list, delete all nodes that have duplicate numbers, leaving onlydistinctnumbers from the original list.

For example,
Given1->2->3->3->4->4->5, return1->2->5.
Given1->1->1->2->3, return2->3.

tag: linkedlist

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) { val = x; }
 * }
 */
class Solution {
    public ListNode deleteDuplicates(ListNode head) {

        if (head == null || head.next == null) return head;

        ListNode dummy = new ListNode(Integer.MAX_VALUE);
        dummy.next = head;
        ListNode prev = dummy, cur = head;
        ListNode temp = dummy;

        while (cur != null && cur.next != null){
            if (prev.val != cur.val && cur.val != cur.next.val){
                temp.next = cur;
                temp = temp.next;
            }

            prev = prev.next;
            cur = cur.next;
        }

        if (prev.val != cur.val){
            temp.next = cur;
            temp = temp.next;
        }
        temp.next = null;

        return dummy.next;
    }
}