Given a linked list, determine if it has a cycle in it. Follow up: Can you solve it without using extra space? 分析: 假设有环?遍历链表将无法走完,假设无环终会走到尾为NULL的位置 让一个指针每次走一个,一个指针每次走两个位置. 假设当中一个为NULL则无环. 假设相遇(必会相遇)了则有环. time,o(n),space,o(1) /** * Definition for sing…

①中文题目 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. 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. 示例 2: 输入:head = [1,2], pos = 0输出:true解释:链表中有一个环,其尾部连接到第一个节点. 示例 3: 输入:head = [1], pos =…

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…

题目描述: 不用辅助空间判断,链表中是否有环 /** * Definition for singly-linked list. * struct ListNode { * int val; * ListNode *next; * ListNode(int x) : val(x), next(NULL) {} * }; */ /*一个指针走的快 一个指针走得慢*/ class Solution { public: bool hasCycle(ListNode *head) { if(head ==…

Given a linked list, determine if it has a cycle in it. Follow up:Can you solve it without using extra space? 题目标签:Linked List 题目给了我们一个 Linked List,让我们判断它是否循环. 利用快,慢指针,快指针一次走2步,慢指针一次走1步,如果循环,快慢指针一定会相遇. Java Solution: Runtime beats 98.15% 完成日期:06/09/2…

Given a linked list, determine if it has a cycle in it. Follow up:Can you solve it without using extra space? 判断一个链表是否存在环,维护快慢指针就可以,如果有环那么快指针一定会追上慢指针,代码如下: class Solution { public: bool hasCycle(ListNode *head) { ListNode * slow, * fast; slow = fast…

这是悦乐书的第176次更新,第178篇原创 01 看题和准备 今天介绍的是LeetCode算法题中Easy级别的第35题(顺位题号是141).给定一个链表,确定它是否有一个循环. 本次解题使用的开发工具是eclipse,jdk使用的版本是1.8,环境是win7 64位系统,使用Java语言编写和测试. 02 理解题意 什么样结构的链表才算是拥有一个循环呢? 链表中某一节点的引用指向了当前链表中已经存在的另一节点时,此链表存在循环. ListNode L = new ListNode(1); Li…

Write a program to check whether a given number is an ugly number. Ugly numbers are positive numbers whose prime factors only include 2, 3, 5. For example, 6, 8 are ugly while 14 is not ugly since it includes another prime factor 7. Note that 1 is ty…

Given a binary tree, find its maximum depth. The maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node. 求二叉树深度,直接看代码: /** * Definition for a binary tree node. * struct TreeNode { * int val; * Tr…

判断链表中是否有环 来源:https://leetcode.com/problems/linked-list-cycle Given a linked list, determine if it has a cycle in it. 一块一慢两个指针,如果有环,两个指针必定会在某个时刻相同且都不为空 Java /** * Definition for singly-linked list. * class ListNode { * int val; * ListNode next; * List…