leetcode算法，我写的错的 求指导为什么。

Question

求解：

Answer 1

 /** 
 * Definition for ListNode 
 * public class ListNode { 
 *     int val; 
 *     ListNode next; 
 *     ListNode(int x) { 
 *         val = x; 
 *         next = null; 
 *     } 
 * } 
 */  
public class Solution {  
    /** 
     * @param ListNode head is the head of the linked list 
     * @return: ListNode head of linked list 
     */  
    public static ListNode deleteDuplicates(ListNode head) {   
        // write your code here  
        if(head==null){  
            return null;  
        }  
        ListNode list=head;  
        while(list.next!=null){  
            if(list.val==list.next.val){  
                if(list.next.next==null){  
                    list.next=null;  
                }else{  
                    ListNode node=list.next;  
                    list.next=node.next;  
                }  
            }else{  
                list=list.next;  
            }  
        }  
        return head;  

    }    
}