leetcode：82. Remove Duplicates from Sorted List II（Java）解答

Posted 2022-12-04 boy_nihao

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原文地址：http://blog.csdn.net/u012975705/article/details/50411033
题目地址：https://leetcode.com/problems/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.

解法（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 helper = new ListNode(0);
        ListNode pre = helper;
        boolean isDup = false;
        while (head != null && head.next != null) 
            if (head.val == head.next.val) 
                isDup = true;
             else if (isDup) 
                isDup = false;
             else 
                pre.next = head;
                pre = pre.next;
            
            head = head.next;
        
        if (!isDup) 
            pre.next = head;
            pre = pre.next;
         else 
            pre.next = null;
        
        return helper.next;