p108 有序链表删除重复节点(leetcode 82)

Posted 2021-03-02 repinkply

一：解题思路

Time:O(n),Space:O(1)

二：完整代码示例 (C++版和Java版)

C++:

class Solution {
public:
    ListNode* deleteDuplicates(ListNode* head) 
    {
        ListNode* dummy = new ListNode(0);
        dummy->next = head;
        ListNode* prev = dummy;
        ListNode* cur = prev->next;

        while (cur!=NULL)
        {
            while (cur->next != NULL && cur->val == cur->next->val) cur = cur->next;
            if (prev->next != cur) prev->next = cur->next;
            else prev = prev->next;
            cur = prev->next;
        }

        return dummy->next;
    }
};

Java:

class Solution {
        public ListNode deleteDuplicates(ListNode head) 
        {
               ListNode dummy=new ListNode(0);
               dummy.next=head;
               ListNode prev=dummy;
               ListNode cur=prev.next;
               while (cur!=null)
               {
                   while (cur.next!=null && cur.val==cur.next.val) cur=cur.next;
                   if(prev.next!=cur) prev.next=cur.next;
                   else prev=prev.next;
                   cur=prev.next;
               }
               
               return dummy.next;
        }
    }