LeetCode 删除排序链表中的重复元素 II （难度：中等）

版权声明：欢迎提问：[email protected] https://blog.csdn.net/include_heqile/article/details/81945645

https://leetcode-cn.com/problems/remove-duplicates-from-sorted-list-ii/description/

我的解决方案：

class ListNode {
     int val;
     ListNode next;
     ListNode(int x) { val = x; }
} 
public class Solution {
    public static  ListNode deleteDuplicates(ListNode head) {
        //处理空链表和单元素链表
        if(head==null||head.next==null) return head;
        boolean first = true;
        ListNode res = null;
        ListNode result = null;
        int tmp;
        for(;head.next!=null;) { 
            //这个while循环会找到一个不重复的节点
            while(head.next==null&&head.val==head.next.val) {
                tmp=head.val;
                while(head!=null&&head.val==tmp)
                    head=head.next; 
                if(head==null) {
                    if(res!=null)
                        //在结果最后加上空节点
                        res.next=head;
                    return result;
                } 
            } 
            if(first){
                res = head;
                //因为res需要发生变化，所以让result作为最终返回结果
                result=res;
                first=false;
            }
            else {
                res.next=head;
                res=res.next;
            } 
            head=head.next;
            if(head==null) break;
        }
        return result;
    }
    public static void main(String[] args) {
        ListNode head= new ListNode(1);
        head.next=new ListNode(2);
        head.next.next=new ListNode(3);
        head.next.next.next=new ListNode(3);
        head.next.next.next.next=new ListNode(4);
        head.next.next.next.next.next=new ListNode(4);
        head.next.next.next.next.next.next=new ListNode(5);
        deleteDuplicates(head);
    }
}