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.

 

每个节点与前驱节点还有后继相比较，若有一个相等，就跳过这个节点。

 

1 /** 2  * Definition for singly-linked list. 3  * public class ListNode { 4  *     int val; 5  *     ListNode next; 6  *     ListNode(int x) { 7  *         val = x; 8  *         next = null; 9  *     }10  * }11  */12 public class Solution {13     public ListNode deleteDuplicates(ListNode head) {14         if (head == null || head.next == null) {15             return head;16         }17         ListNode start = new ListNode(head.val - 1);18         ListNode temp=start;19         ListNode curr=head;20         int prev=start.val;21         int next=head.next.val;22         while (curr.next != null) {23             if (curr.val != prev && curr.val != curr.next.val) {24                 prev = curr.val;25                 temp.next = curr;26                 temp=temp.next;27                 curr = curr.next;28             } else {29                 prev=curr.val;30                 curr=curr.next;31                 if(curr.next!=null) next=curr.next.val;32             }33         }34         if (curr.val != prev) {35             temp.next = curr;36         }else temp.next=null;37         return start.next;38         39     }40 }