Remove Duplicates from Sorted List II

Remove Duplicates from Sorted List II

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

For example,
Given 1->2->3->3->4->4->5, return 1->2->5.
Given 1->1->1->2->3, return 2->3.

Java代码：

/**
 * 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) {
        if (null == head || null == head.next)
			return head;
		ListNode new_head = new ListNode(0);
		new_head.next = head;
		ListNode tmp = new_head;
		while (true) {
			if (tmp.next != null && tmp.next.next != null
					&& tmp.next.next.next != null) {
				if (tmp.next.val == tmp.next.next.val
						&& tmp.next.val == tmp.next.next.next.val) {
					tmp.next = tmp.next.next; // 跳过后一个
				} else if (tmp.next.val == tmp.next.next.val) {
					tmp.next = tmp.next.next.next; // 跳过后两个
				} else {
					tmp = tmp.next; // 跳过后一个
				}
			}else if(tmp.next != null && tmp.next.next !=null){
				if(tmp.next.val ==tmp.next.next.val)
					tmp.next =null;
				else
					tmp = tmp.next.next;
			}else{
				break;
			}
		}
		head = new_head.next;
		new_head = null;
		return head;
    }
}