Remove Nth Node From End of List
2022/4/4 20:19:01
本文主要是介绍Remove Nth Node From End of List,对大家解决编程问题具有一定的参考价值,需要的程序猿们随着小编来一起学习吧!
Source
Given a linked list, remove the nth node from the end of list and return its head. Note The minimum number of nodes in list is n. Example Given linked list: 1->2->3->4->5->null, and n = 2. After removing the second node from the end, the linked list becomes 1->2->3->5->null. Challenge O(n) time
题解
简单题,使用快慢指针解决此题,需要注意最后删除的是否为头节点。让快指针先走n
步,直至快指针走到终点,找到需要删除节点之前的一个节点,改变node->next
域即可。
C++
/** * Definition of ListNode * class ListNode { * public: * int val; * ListNode *next; * ListNode(int val) { * this->val = val; * this->next = NULL; * } * } */ class Solution { public: /** * @param head: The first node of linked list. * @param n: An integer. * @return: The head of linked list. */ ListNode *removeNthFromEnd(ListNode *head, int n) { if (NULL == head || n < 1) { return NULL; } ListNode *dummy = new ListNode(0); dummy->next = head; ListNode *preDel = dummy; for (int i = 0; i != n; ++i) { if (NULL == head) { return NULL; } head = head->next; } while (head) { head = head->next; preDel = preDel->next; } preDel->next = preDel->next->next; return dummy->next; } };
Java
/** * Definition for singly-linked list. * public class ListNode { * int val; * ListNode next; * ListNode(int x) { val = x; } * } */ class Solution { public ListNode removeNthFromEnd(ListNode head, int n) { if (head == nul) return head; ListNode dummy = new ListNode(0); dummy.next = head; ListNode fast = head; ListNode slow = dummy; for (int i = 0; i < n; i++) { fast = fast.next; } while(fast != null) { fast = fast.next; slow = slow.next; } // gc friendly // ListNode toBeDeleted = slow.next; slow.next = slow.next.next; // toBeDeleted.next = null; // toBeDeleted = null; return dummy.next; } }
源码分析
引入dummy节点后画个图分析下就能确定head和preDel的转移关系了。 注意 while 循环中和快慢指针初始化的关系,否则容易在顺序上错一。
复杂度分析
极限情况下遍历两遍链表,时间复杂度为 O(n).
这篇关于Remove Nth Node From End of List的文章就介绍到这儿,希望我们推荐的文章对大家有所帮助,也希望大家多多支持为之网!
- 2024-06-15matplotlib作图不显示3D图,怎么办?
- 2024-06-1503-Loki 日志监控
- 2024-06-1504-让LLM理解知识 -Prompt
- 2024-06-05做软件测试需要懂代码吗?
- 2024-06-0514-ShardingSphere的分布式主键实现
- 2024-06-03为什么以及如何要进行架构设计权衡?
- 2024-05-31全网首发第二弹!软考2024年5月《软件设计师》真题+解析+答案!(11-20题)
- 2024-05-31全网首发!软考2024年5月《软件设计师》真题+解析+答案!(21-30题)
- 2024-05-30【Java】百万数据excel导出功能如何实现
- 2024-05-30我们小公司,哪像华为一样,用得上IPD(集成产品开发)?