C++实现LeetCode(141.单链表中的环)
[LeetCode] 141. Linked List Cycle 单链表中的环
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 the linked list.
Example 1:
Input: head = [3,2,0,-4], pos = 1
Output: true
Explanation: There is a cycle in the linked list, where tail connects to the second node.
Example 2:
Input: head = [1,2], pos = 0
Output: true
Explanation: There is a cycle in the linked list, where tail connects to the first node.
Example 3:
Input: head = [1], pos = -1
Output: false
Explanation: There is no cycle in the linked list.
Follow up:
Can you solve it using O(1) (i.e. constant) memory?
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(ListNode *head) {
ListNode *slow = head, *fast = head;
while (fast && fast->next) {
slow = slow->next;
fast = fast->next->next;
if (slow == fast) return true;
}
return false;
}
};
Java 解法：
public class Solution {
public boolean hasCycle(ListNode head) {
ListNode slow = head, fast = head;
while (fast != null && fast.next != null) {
slow = slow.next;
fast = fast.next.next;
if (slow == fast) return true;
}
return false;
}
}
Github 同步地址：
https://github.com/grandyang/leetcode/issues/141
类似题目：
参考资料：
https://leetcode.com/problems/linked-list-cycle/
https://leetcode.com/problems/linked-list-cycle/discuss/44489/O(1)-Space-Solution
到此这篇关于C++实现LeetCode(141.单链表中的环)的文章就介绍到这了,更多相关C++实现单链表中的环内容请搜索我们以前的文章或继续浏览下面的相关文章希望大家以后多多支持我们！
相关推荐
-
C++实现LeetCode(102.二叉树层序遍历)
[LeetCode] 102. Binary Tree Level Order Traversal 二叉树层序遍历 Given a binary tree, return the level order traversal of its nodes' values. (ie, from left to right, level by level). For example: Given binary tree {3,9,20,#,#,15,7}, 3 / \ 9 20 / \ 15
-
C++实现LeetCode(105.由先序和中序遍历建立二叉树)
[LeetCode] 105. Construct Binary Tree from Preorder and Inorder Traversal 由先序和中序遍历建立二叉树 Given preorder and inorder traversal of a tree, construct the binary tree. Note: You may assume that duplicates do not exist in the tree. For example, given preor
-
C++实现LeetCode(103.二叉树的之字形层序遍历)
[LeetCode] 103. Binary Tree Zigzag Level Order Traversal 二叉树的之字形层序遍历 Given a binary tree, return the zigzag level order traversal of its nodes' values. (ie, from left to right, then right to left for the next level and alternate between). For example
-
C++实现LeetCode(100.判断相同树)
[LeetCode] 100. Same Tree 判断相同树 Given two binary trees, write a function to check if they are the same or not. Two binary trees are considered the same if they are structurally identical and the nodes have the same value. Example 1: Input: 1
-
C++实现LeetCode(101.判断对称树)
[LeetCode] 101.Symmetric Tree 判断对称树 Given a binary tree, check whether it is a mirror of itself (ie, symmetric around its center). For example, this binary tree is symmetric: 1 / \ 2 2 / \ / \ 3 4 4 3 But the following is not: 1 / \ 2
-
C++实现LeetCode(107.二叉树层序遍历之二)
[LeetCode] 107. Binary Tree Level Order Traversal II 二叉树层序遍历之二 Given the root of a binary tree, return the bottom-up level order traversal of its nodes' values. (i.e., from left to right, level by level from leaf to root). Example 1: Input: root = [3
-
C++实现LeetCode(142.单链表中的环之二)
[LeetCode] 142. Linked List Cycle II 单链表中的环之二 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-indexe
-
C++实现LeetCode(141.单链表中的环)
[LeetCode] 141. Linked List Cycle 单链表中的环 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.
-
python实现单链表中删除倒数第K个节点的方法
本文实例为大家分享了python实现单链表中删除倒数第K个节点的具体代码,供大家参考,具体内容如下 题目: 给定一个链表,删除其中倒数第k个节点. 代码: class LinkedListAlgorithms(object): def __init__(self): pass def rm_last_kth_node(self, k, linked_list): # 删除倒数第 K 个节点,针对单链表的 if linked_list.is_empty(): print 'The given li
-
java实现单链表中的增删改
本文实例为大家分享了java实现单链表中增删改的具体代码,供大家参考,具体内容如下 什么是链表 链表是有序的列表,但是它在内存中是存储如下 小结: 链表是以节点的方式来存储,是链式存储 每个节点包含data 域, next 域:指向下一个节点. 如图:发现链表的各个节点不一定是连续存储. 链表分带头节点的链表和没有头节点的链表,根据实际的需求来确定 单链表(带头结点) 逻辑结构示意图如下 单链表的增删改应用实例 使用带head 头的单向链表实现——三国英雄排行榜管理完成对英雄人物的增删改查操作
-
java实现单链表中是否有环的方法详解
这是一道微软经典笔试题,就是两个指针h1,h2都从头开始遍历单链表,h1每次向前走1步,h2每次向前走2步,如果h2碰到了NULL,说明环不存在:如果h2碰到本应在身后的h1说明环存在(也就是发生了套圈). 如果环不存在,一定是h2先碰到NULL: 如果环存在,h2与h1一定会相遇,而且相遇的点在环内:h2比h1遍历的速度快,一定不会在开始的那段非环的链表部分相遇,所以当h1,h2都进入环后,h2每次移动都会使h2与h1之间在前进方向上的差距缩小1,最后,会使得h1和h2差距减少为0,也即相遇
-
Python实现单链表中元素的反转
给定一个单链表,将其反转.其实很容易想到,只需要修改每个结点的指针指向:即令后一个结点指向前一个结点,并且将表头指针指向最后一个结点即可. 这个过程可以用循环实现,也可以用递归来实现. 1.用循环来实现: class LNode: def __init__(self, elem): self.elem = elem self.pnext = None def reverse(head): if head is None or head.pnex
-
C语言中如何实现单链表删除指定结点
目录 单链表删除指定结点 链表的删除结点(各种方法) 链表中删除第i个结点 删除与链表中与a相同的结点 删除链表中重复元素 单链表删除指定结点 在单链表中删除指定的结点.这里单链表是用尾插法建立的,因为尾插法输出的顺序与输入的顺序是相同的. #include <bits/stdc++.h> using namespace std; typedef struct node { int data; struct node *next; }no; int main() { no *head,*tai
-
一篇文章带你玩转JAVA单链表
目录 一.链表 1. 概念 2. 结构 二.单向不带头非循环链表 1. 概念及结构 2. 链表的实现 三.链表面试题 四.总结 一.链表 1. 概念 链表是一种物理存储结构上非连续的存储结构,数据元素的逻辑顺序是通过链表中的引用链接次序实现的 上章介绍到顺序表适合用作查询和修改,而不适合用作插入和删除.并且它增容时容易造成空间浪费.而链表则具有以下的特点 适合用作插入和删除随用随取,避免了空间的浪费不适合用作查询和修改 2. 结构 链表其实可以想象成一条被打了一些结的绳子 而实际上,链表就是由一
-
Node.js环境下JavaScript实现单链表与双链表结构
单链表(LinkedList)的javascript实现 npmjs相关库: complex-list.smart-list.singly-linked-list 编程思路: add方法用于将元素追加到链表尾部,借由insert方法来实现: 注意各个函数的边界条件处理. 自己的实现: SingleNode.js (function(){ "use strict"; function Node(element){ this.element = element; this.next = n
-
C语言之单链表的插入、删除与查找
单链表是一种链式存取的数据结构,用一组地址任意的存储单元存放线性表中的数据元素.要实现对单链表中节点的插入.删除与查找的功能,就要先进行的单链表的初始化.创建和遍历,进而实现各功能,以下是对单链表节点的插入.删除.查找功能的具体实现: #include<stdio.h> #include<stdlib.h> #include<string.h> typedef int ElemType; /** *链表通用类型 *ElemType 代表自定义的数据类型 *struct