LeetCode || Remove Duplicates from Sorted List II

最新推荐文章于 2025-05-22 22:12:37 发布

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最新推荐文章于 2025-05-22 22:12:37 发布

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分类专栏： LeetCode 文章标签： Linked List LeetCode

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本博客介绍如何在给定的排序链表中删除所有出现重复数值的节点，只保留唯一数值。

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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.

题目链接

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution {
public:
    ListNode* deleteDuplicates(ListNode* head) {
        //if(head == NULL || head->next == NULL)
        //    return head;
            
        ListNode* start = head;
        ListNode* startParent = NULL;
        ListNode* curr = head;
        
        while(curr!=NULL)
        {
            if(curr->next == NULL)//
            {
                if(start != curr)
                {
                    if(startParent == NULL)//删除的是头结点
                        head = curr->next;
                    else
                        startParent->next = curr->next;
                }
                break;
            }
            
            if(curr->next->val == curr->val)//如果相等，则判断相等的数据有多少
                curr = curr->next;
            else
            {
                //delete nodes from start to end
                if(start!=curr)
                {
                    if(startParent == NULL)//删除的是头结点
                    {
                        head = curr->next;
                        startParent = NULL;
                    }
                    else
                    {
                        startParent->next = curr->next;
                        //startParent = curr; //注意此时不要改变startParent的取值。
                    }
                }
                else
                    startParent = curr;
                
                curr = curr->next;
                start = curr;
            }
            
        }
        

        return head;
    }
};