Lintcode174-Remove Nth Node From End of List-Easy
174. Remove Nth Node From End of List
Given a linked list, remove the nth node from the end of list and return its head.
Example
Example 1:
Input: list = 1->2->3->4->5->null, n = 2
Output: 1->2->3->5->null
Example 2:
Input: list = 5->4->3->2->1->null, n = 2
Output: 5->4->3->1->null
Challenge
Can you do it without getting the length of the linked list?
Notice
The minimum number of nodes in list is n.
双指针法:
定义快慢指针,先同时指向dummy结点。快指针(head)先比慢指针(preDelete)多走n步。
然后,快慢指针一起走,当快指针指向链表最后一个结点时,慢指针指向就是要删除结点的前一个结点。
ps: 对单向链表而言,删除结点时,必须操作要删除结点的前一个结点,而不是要删除的结点本身,否则无法使要删除结点的前一个和后一个结点连接。这也是这个题中,慢指针指向要删除结点的前一个结点,也因此推出快指针的临界位置。
代码:
public ListNode removeNthFromEnd(ListNode head, int n) {
ListNode dummy = new ListNode(-1);
dummy.next = head;
head = dummy;
ListNode preDelete = dummy;
for (int i = 1; i <= n; i++) {
head = head.next;
}
while (head.next != null) {
head = head.next;
preDelete = preDelete.next;
}
preDelete.next = preDelete.next.next;
return dummy.next;
}
考虑特殊情况(n <= 0, head == null)
public class Solution {
public ListNode removeNthFromEnd(ListNode head, int n) {
if (n <= 0) {
return null;
}
ListNode dummy = new ListNode(0);
dummy.next = head;
ListNode preDelete = dummy;
for (int i = 0; i < n; i++) {
if (head == null) {
return null;
}
head = head.next;
}
while (head != null) {
head = head.next;
preDelete = preDelete.next;
}
preDelete.next = preDelete.next.next;
return dummy.next;
}
}
Lintcode174-Remove Nth Node From End of List-Easy的更多相关文章
- 63. Swap Nodes in Pairs && Rotate List && Remove Nth Node From End of List
Swap Nodes in Pairs Given a linked list, swap every two adjacent nodes and return its head. For exam ...
- LeetCode: Remove Nth Node From End of List 解题报告
Remove Nth Node From End of List Total Accepted: 46720 Total Submissions: 168596My Submissions Quest ...
- Merge Two Sorted Lists & Remove Nth Node From End of List
1.合并两个排好序的list Merge Two Sorted Lists Merge two sorted linked lists and return it as a new list. The ...
- leetcode-algorithms-19 Remove Nth Node From End of List
leetcode-algorithms-19 Remove Nth Node From End of List Given a linked list, remove the n-th node fr ...
- 61. Rotate List(M);19. Remove Nth Node From End of List(M)
61. Rotate List(M) Given a list, rotate the list to the right by k places, where k is non-negative. ...
- 《LeetBook》leetcode题解(19):Remove Nth Node From End of List[E]——双指针解决链表倒数问题
我现在在做一个叫<leetbook>的开源书项目,把解题思路都同步更新到github上了,需要的同学可以去看看 这个是书的地址: https://hk029.gitbooks.io/lee ...
- 【LeetCode】19. Remove Nth Node From End of List (2 solutions)
Remove Nth Node From End of List Given a linked list, remove the nth node from the end of list and r ...
- LeetCode解题报告—— 4Sum & Remove Nth Node From End of List & Generate Parentheses
1. 4Sum Given an array S of n integers, are there elements a, b, c, and d in S such that a + b + c + ...
- Leetcode 题目整理-4 Longest Common Prefix & Remove Nth Node From End of List
14. Longest Common Prefix Write a function to find the longest common prefix string amongst an array ...
- 刷题19. Remove Nth Node From End of List
一.题目说明 这个题目是19. Remove Nth Node From End of List,不言自明.删除链表倒数第n个元素.难度是Medium! 二.我的解答 链表很熟悉了,直接写代码. 性能 ...
随机推荐
- CF653F Paper task
题目链接:洛谷 首先我们不考虑本质不同这个限制. 既然不能直接用栈乱搞,我们就可以用一个前缀和的套路了. 我们将(设为1,将)设为-1,记前缀和为$s_i$,则$[i,j]$这一段是回文子串当且仅当 ...
- mybatisplus ssm配置要点
本以为不难,但也捣鼓了大半天,记录要点如下: 在pom中引入mybatis plus相关包 <!-- mybatis-plus框架包 start --> <dependency> ...
- pwn学习日记Day1 基础知识积累
ida / od 窗口(针对od操作) 反汇编窗口:显示被调试程序的反汇编代码,标题栏上的地址.HEX 数据.反汇编.注释可以通过在窗口中右击出现的菜单 界面选项->隐藏标题 或 显示标题 来进 ...
- 一个农民工混迹于 IT 行业多年后的泣血总结
一看题目,你心里一定闪出一个想法,这又是一篇软文吧,是不是,不想辩别了,自己判断吧哈哈.这是根据本人真实经历所写的一篇总结.假如你满足你的现状,这就是一篇软文,请立刻关闭此文章,继续你现在的生活. ...
- Asp.net Image控件显示Bitmap生成图像
from:https://blog.csdn.net/qq_29011299/article/details/81137980 using(Bitmap bmp=new Bitmap(300,50)) ...
- puppeteer(三)常用API
1.Puppeteer 简介 Puppeteer 是一个node库,他提供了一组用来操纵Chrome的API, 通俗来说就是一个 headless chrome浏览器 (当然你也可以配置成有UI的,默 ...
- git宝典—应付日常工作使用足够的指北手册
最近公司gitlab又迁移,一堆git的命令骚操作,然鹅git命令,感觉还是得复习下——其实,git现在界面操作工具蛮多,比如intellij 自带的git操作插件就不错,gitlab github ...
- KeepAlived+HaProxy+MyCat+Percona双机热备PXC集群
一.搭建PXC集群 1.环境:centos7+PXC5.7.21+mycat1.6.5 2.卸载mariadb rpm -qa | grep mariadb* yum -y remove mariad ...
- JQuery小知识
一.禁用鼠标右键 $(document).ready(function() { $(document).bind("contextmenu", function(e) { retu ...
- springmvc配置之mvc:annotation-driven
为了简化springmvc配置,spring同时引入了mvc namespace, 配置了 <mvc:annotation-driven/> spring会默认注册a RequestMap ...