Given a linked list, determine if it has a cycle in it. Follow up:Can you solve it without using extra space? 给定一个链表,判断是否有环存在.Follow up: 不使用额外空间. 解法:双指针,一个慢指针每次走1步,一个快指针每次走2步的,如果有环的话,两个指针肯定会相遇. Java: public class Solution { public boolean hasCycle(Li…

Given a linked list, return the node where the cycle begins. If there is no cycle, return null. Follow up:Can you solve it without using extra space? 141. Linked List Cycle 的拓展,这题要返回环开始的节点,如果没有环返回null. 解法:双指针,还是用快慢两个指针,相遇时记下节点.参考:willduan的博客 Java: pu…

Given a linked list, return the node where the cycle begins. If there is no cycle, return null. Follow up: Can you solve it without using extra space? 这个求单链表中的环的起始点是之前那个判断单链表中是否有环的延伸,可参见我之前的一篇文章 (http://www.cnblogs.com/grandyang/p/4137187.html). 还是要设…

Given a linked list, determine if it has a cycle in it. Follow up: Can you solve it without using extra space? 这道题是快慢指针的经典应用.只需要设两个指针,一个每次走一步的慢指针和一个每次走两步的快指针,如果链表里有环的话,两个指针最终肯定会相遇.实在是太巧妙了,要是我肯定想不出来.代码如下: C++ 解法: class Solution { public: bool hasCycle…

题目要求 Linked List Cycle Given a linked list, determine if it has a cycle in it. Follow up: Can you solve it without using extra space? 如何判断一个单链表中有环? Linked List Cycle II Given a linked list, return the node where the cycle begins. If there is no cycle…

2.6 Given a circular linked list, implement an algorithm which returns the node at the beginning of the loop.DEFINITIONCircular linked list: A (corrupt) linked list in which a node's next pointer points to an earlier node, so as to make a loop in the…

Given a linked list, return the node where the cycle begins. If there is no cycle, return null. Follow up:Can you solve it without using extra space? 思路 这题是Linked List Cycle的进阶版 Given a linked list, determine if it has a cycle in it. bool hasCycle(Li…

1.Linked List Cycle 题目链接 题目要求: Given a linked list, determine if it has a cycle in it. Follow up: Can you solve it without using extra space? 刚看到这道题,很容易写出下边的程序: bool hasCycle(ListNode *head) { ListNode *a = head, *b = head; while(a) { b = a->next; wh…

Given a linked list, determine if it has a cycle in it. To represent a cycle in the given linked list, we use an integer poswhich represents the position (0-indexed) in the linked list where tail connects to. If pos is -1, then there is no cycle in t…

Given a linked list, return the node where the cycle begins. If there is no cycle, return null. To represent a cycle in the given linked list, we use an integer pos which represents the position (0-indexed) in the linked list where tail connects to.…

描述 给定一个链表,判断它是否有环. 样例 给出 -21->10->4->5, tail connects to node index 1,返回 true. 这里解释下,题目的意思,在英文原题中,tail connects to node index 1 表示的是节点 5 还要链接回索引号 为 1 的节点. 一个典型的带环链表如下: 挑战 不要使用额外的空间 代码 GitHub 的源代码,请访问下面的链接: https://github.com/cwiki-us/java-tutoria…

Given a linked list, return the node where the cycle begins. If there is no cycle, returnnull. Follow up:Can you solve it without using extra space? 题意:给定链表,若是有环,则返回环开始的节点,没有则返回NULL 思路:题目分两步走,第一.判断是否有环,第二若是有,找到环的起始点.关于第一点,可以参考之前的博客 Linked list cycle.…

Given a linked list, return the node where the cycle begins. If there is no cycle, return null. To represent a cycle in the given linked list, we use an integer pos which represents the position (0-indexed) in the linked list where tail connects to.…

Given a linked list, determine if it has a cycle in it. To represent a cycle in the given linked list, we use an integer pos which represents the position (0-indexed) in the linked list where tail connects to. If pos is -1, then there is no cycle in…

142. 环形链表 II 142. Linked List Cycle II 题目描述 给定一个链表,返回链表开始入环的第一个节点.如果链表无环,则返回 null. 为了表示给定链表中的环,我们使用整数 pos 来表示链表尾连接到链表中的位置(索引从 0 开始).如果 pos 是 -1,则在该链表中没有环. 说明: 不允许修改给定的链表. LeetCode142. Linked List Cycle II 示例 1: 输入: head = [3,2,0,-4], pos = 1 输出: tail…

141. 环形链表 141. Linked List Cycle 题目描述 给定一个链表,判断链表中是否有环. 为了表示给定链表中的环,我们使用整数 pos 来表示链表尾连接到链表中的位置(索引从 0 开始).如果 pos 是 -1,则在该链表中没有环. 每日一算法2019/5/22Day 19LeetCode141. Linked List Cycle 示例 1: 输入: head = [3,2,0,-4], pos = 1 输出: true 解释: 链表中有一个环,其尾部连接到第二个节点.…

Given a linked list, determine if it has a cycle in it. ExampleGiven -21->10->4->5, tail connects to node index 1, return true Challenge Follow up:Can you solve it without using extra space? LeetCode上的原题,请参见我之前的博客Linked List Cycle. class Solution…

141. Linked List Cycle Given a linked list, determine if it has a cycle in it. Follow up:Can you solve it without using extra space? 利用快慢指针,如果相遇则证明有环 注意边界条件: 如果只有一个node. public class Solution { public boolean hasCycle(ListNode head) { if(head==null |…

今天星期天,准备好周一的PPT内容,再回来做题,以后考虑周末做一个APP或者微信帐号玩吧. 回到题目, Linked List Cycle,一个检查单项链表是否有环路的问题. 题目周五的时候就简单做过,可是链表中带入了一个val常量,当时误以为是要检查是否有重复值,WA了. 早上再试了会,缓过来,其实还是比较地址指针. 最开始写的一个简单方法,只能判断是否与头指针重复,但是如果环路从中间开始就判断不到了,再想了10多分钟,有一个O(n^2)的算法,每次从第一个指针开始,判断后面k-1个指针是否相…

Linked List Sorting (链表)   A linked list consists of a series of structures, which are not necessarily adjacent in memory. We assume that each structure contains an integer key and a Next pointer to the next structure. Now given a linked list, you ar…

LeetCode解题报告:Linked List Cycle && Linked List Cycle II 1题目 Linked List Cycle Given a linked list, determine if it has a cycle in it. Follow up: Can you solve it without using extra space? Linked List Cycle II Given a linked list, return the node w…

Problem: Given a linked list, determine if it has a cycle in it. Follow up:Can you solve it without using extra space? https://oj.leetcode.com/problems/linked-list-cycle/ Problem II: Given a linked list, return the node where the cycle begins. If the…

Linked List Cycle Given a linked list, determine if it has a cycle in it. Follow up:Can you solve it without using extra space?   Linked List Cycle II Given a linked list, return the node where the cycle begins. If there is no cycle, return null. Fol…

141. Linked List Cycle Given a linked list, determine if it has a cycle in it. Follow up:Can you solve it without using extra space? /** * Definition for singly-linked list. * struct ListNode { * int val; * ListNode *next; * ListNode(int x) : val(x),…

题目: 141.Given a linked list, determine if it has a cycle in it. 142.Given a linked list, return the node where the cycle begins. If there is no cycle, return null. 思路: 带环链表如图所示.设置一个快指针和一个慢指针,快指针一次走两步,慢指针一次走一步.快指针先进入环,慢指针后进入环.在进入环后,可以理解为快指针追赶慢指针,由于两个指…

题目: Given a linked list, determine if it has a cycle in it. Follow up: Can you solve it without using extra space? 解题思路: 判断链表有无环,可用快慢指针进行,快指针每次走两步,慢指针每次走一步,如果快指针追上了慢指针,则存在环,否则,快指针走到链表末尾即为NULL是也没追上,则无环. 为什么快慢指针可以判断有无环? 因为快指针先进入环,在慢指针进入之后,如果把慢指针看作在前面,快…

题目: Given a linked list, return the node where the cycle begins. If there is no cycle, return null. Follow up: Can you solve it without using extra space? 解题思路: 判断链表有无环,可用快慢指针进行,快指针每次走两步,慢指针每次走一步,如果快指针追上了慢指针,则存在环,否则,快指针走到链表末尾即为NULL是也没追上,则无环. 为什么快慢指针可…

判断链表有环,环的入口结点,环的长度 1.判断有环: 快慢指针,一个移动一次,一个移动两次 2.环的入口结点: 相遇的结点不一定是入口节点,所以y表示入口节点到相遇节点的距离 n是环的个数 w + n + y = 2 (w + y) 经过化简,我们可以得到:w  = n - y; https://www.cnblogs.com/zhuzhenwei918/p/7491892.html 3.环的长度: 从入口结点或者相遇的结点移动到下一次再碰到这个结点计数 https://blog.csdn.ne…

Given a linked list, return the node where the cycle begins. If there is no cycle, return null. 解题: 寻找单链表中环的入口,如果不存在环则返回null. 假设单链表有环,先利用判断单链表是否有环(Linked List Cycle)的方法,找到快慢指针的交点. 假设环的入口在第K个结点处,那么此时快慢指针的交点,距离环入口,还差k个距离. 快慢指针相交后,在链表头位置同时启动另一个指针target,…

引入 快慢指针经常用于链表(linked list)中环(Cycle)相关的问题.LeetCode中对应题目分别是: 141. Linked List Cycle 判断linked list中是否有环 142. Linked List Cycle II 找到环的起始节点(entry node)位置. 简介 快指针(fast pointer)和慢指针(slow pointer)都从链表的head出发. slow pointer每次移动一格,而快指针每次移动两格. 如果快慢指针能相遇,则证明链表中有…