leo-yang0201 / leo-yang0201.github.io Goto Github PK

https://leo-yang0201.github.io/leo-yang0201.github.io/2020/03/25/Leetcode-136-Single-Number/

Difficulty : Easy Type: Hash Table,Bit Manipulation Language : Java ClarificationGiven a non-empty array of integers, every element appears twice except for one. Find that single one.

https://leo-yang0201.github.io/leo-yang0201.github.io/2020/04/29/Leetcode-1095-Find-in-Mountain-Array/

Difficulty : Hard Type: Binary Search Language : Java Clarification (This problem is an interactive problem.)* You may recall that an array A is a mountain array if and only if: A.length >= 3 The

https://leo-yang0201.github.io/leo-yang0201.github.io/2020/04/01/Java%E9%9D%A2%E8%AF%95%E9%A2%98%E6%A8%A1%E5%9D%97%E5%8D%81/

介绍下Java内存区域(运行时数据区)JVM在执行Java程序的过程中，会把它管理的内存划分成若干个不同的数据区域。JDK1.8之前：

https://leo-yang0201.github.io/leo-yang0201.github.io/2019/12/16/Leetcode-206-Reverse-Linked-List/

Difficulty : EasyType: Linked ListLanguage : Java Clarification Reverse a singly linked list Possible Solutions IterationSet three LinkNode prev, curr and temp. prev and temp are null at first and

https://leo-yang0201.github.io/leo-yang0201.github.io/2020/03/10/ConcurrentHashMap%E5%92%8CHashtable%E7%9A%84%E5%8C%BA%E5%88%AB/

面试只要是问到多线程相关的知识，这个问题是很常见的，我查了几篇资料然后做了一下总结： 首先HashMap它不是线程安全的，在多线程情况下HashMap可能出现以下线程安全问题： 多线程的put可能导致元素的丢失试验代码： 注：仅作为可能会产生这个问题的样例代码，直接运行不一定会产生问题 123456789101112131415161718192021222324252627282930publi

https://leo-yang0201.github.io/leo-yang0201.github.io/2020/01/31/Leetcode-101-Symmetric-Tree/

Difficulty : EasyType: Binary Tree, DFS, BFSLanguage : Java Clarification Given a binary tree, check whether it is a mirror of itself (ie, symmetric around its center). Possible Solutions 递归注意如果根结

https://leo-yang0201.github.io/leo-yang0201.github.io/2020/03/16/Java%E9%9D%A2%E8%AF%95%E9%A2%98%E6%A8%A1%E5%9D%97%E5%85%AB/

为什么要使用Spring？ 简介 目的：解决企业应用开发的复杂性 功能：使用基本的JavaBean代替EJB，并提供了更多的企业应用功能 范围：任何Java应用 简单来说，Spring是一个轻量级的控制反转（IOC）和面向切面（AOP）的容器框架 轻量 从大小和开销两方面而言Spring都是轻量的。完整的Spring框架可以在一个大小只有1MB多的JAR文件里发布。并且Spring所需的

https://leo-yang0201.github.io/leo-yang0201.github.io/2020/03/08/Leetcode-322-Coin-Change/

Difficulty : Medium Type: Dynamic Programming Language : Java ClarificationYou are given coins of different denominations and a total amount of money amount. Write a function to compute the fewest num

https://leo-yang0201.github.io/leo-yang0201.github.io/2020/04/06/Leetcode-72-Edit-Distance/#more

Difficulty : Hard Type: String,Dynamic Programming Language : Java Clarification Given two words word1 and word2, find the minimum number of operations required to convert word1 to word2. You have the

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Hi, I use this blog to record my daily practice in computer science and data science.

https://leo-yang0201.github.io/leo-yang0201.github.io/2020/03/28/Leetcode-96-Unique-Binary-Search-Trees/#more

Difficulty : Medium Type: tree,Dynamic Programming Language : Java ClarificationGiven n, how many structurally unique BST’s (binary search trees) that store values 1 … n?

https://leo-yang0201.github.io/leo-yang0201.github.io/2020/03/24/Leetcode-%E9%9D%A2%E8%AF%95%E9%A2%9817-16-%E6%8C%89%E6%91%A9%E5%B8%88/

Difficulty : Easy Type: Dynamic Programming Language : Java Clarification一个有名的按摩师会收到源源不断的预约请求，每个预约都可以选择接或不接。在每次预约服务之间要有休息时间，因此她不能接受相邻的预约。给定一个预约请求序列，替按摩师找到最优的预约集合（总预约时间最长），返回总的分钟数。 Possible Solutions 动

https://leo-yang0201.github.io/leo-yang0201.github.io/2020/03/03/Leetcode-1328-Break-a-Palindrome/

Difficulty : MediumType: StringLanguage : Java Clarification Given a palindromic string palindrome, replace exactly one character by any lowercase English letter so that the string becomes the lexico

https://leo-yang0201.github.io/leo-yang0201.github.io/2019/12/16/Leetcode-70-Climbing-Stairs/

Difficulty : EasyType: Dynamic programmingLanguage : Java ClarificationEach time you can either climb 1 step or 2 steps. Find all the distinct ways to climb to the top Possible Solutions 斐波那契数列当n &l

https://leo-yang0201.github.io/leo-yang0201.github.io/2020/03/07/Java%E9%9D%A2%E8%AF%95%E9%A2%98%E6%A8%A1%E5%9D%97%E4%B8%89/

并行和并发有什么区别？ 并行指两个或者多个事件在同一时刻发生，并发是指两个或多个事件在同一时间间隔发生 并行是在不同实体上的多个事件，并发是在同一实体上的多个事件 并发编程的目标是充分的利用处理器的每一个核，以达到最高的处理性能 线程和进程的区别？进程是程序运行和资源分配的基本单位，一个程序至少有一个进程，一个进程至少有一个线程。进程在执行过程中拥有独立的内存单元，而多个线程共享内存单元，减少切

https://leo-yang0201.github.io/leo-yang0201.github.io/2020/03/26/Leetcode-999-Available-Captures-for-Rook/

Difficulty : Easy Type: Array Language : Java ClarificationOn an 8 x 8 chessboard, there is one white rook. There also may be empty squares, white bishops, and black pawns. These are given as characte

https://leo-yang0201.github.io/leo-yang0201.github.io/2020/03/12/Leetcode-53-Maximum-Subarray/

Difficulty : Easy Type: Dynamic Programming, Array, Divide and Conquer Language : Java ClarificationGiven an integer array nums, find the contiguous subarray (containing at least one number) which has

https://leo-yang0201.github.io/leo-yang0201.github.io/2020/02/15/Leetcode-62-Unique-Paths/

Difficulty : MediumType: Dynamic ProgrammingLanguage : Java Clarification A robot is located at the top-left corner of a m x n grid (marked ‘Start’ in the diagram below). The robot can only move eith

https://leo-yang0201.github.io/leo-yang0201.github.io/2020/03/09/Java%E9%9D%A2%E8%AF%95%E9%A2%98%E6%A8%A1%E5%9D%97%E4%BA%94/

throw和throws的区别？throws是用来声明一个方法可能抛出的所有异常信息，throws是将异常声明但是不处理，而是将异常往上传，谁调用我就交给谁处理，而throw则是指抛出的一个具体的异常类型 final、finally、finalize有什么区别？ final可以修饰类、变量、方法，修饰类表示该类不可以继承，修饰变量表示该变量是常量，不能被重新赋值，修饰方法表示此方法不可以被重写 f

https://leo-yang0201.github.io/leo-yang0201.github.io/2020/03/09/Java%E9%9D%A2%E8%AF%95%E9%A2%98%E6%A8%A1%E5%9D%97%E5%9B%9B/

什么是反射？反射主要是指程序可以访问、检测和修改它本身状态或行为的一种能力 Java反射机制主要提供以下功能： 在运行时判断任意一个对象所属的类 在运行时构造任意一个类的对象 在运行时判断任意一个类所具有的成员变量和方法 在运行时调用任意一个对象的方法 什么是Java序列化？什么情况需要序列化？序列化本质上就是把对象内存中的数据按照一定规则，变成一系列的字节数据，然后把这些字节数据写入到流中，

https://leo-yang0201.github.io/leo-yang0201.github.io/2020/03/30/Leetcode-46-Permulations/

Difficulty : Medium Type: 回溯算法 Language : Java Clarification Given a collection of distinct integers, return all possible permutations.

https://leo-yang0201.github.io/leo-yang0201.github.io/2020/02/10/Leetcode-103-Binary-Tree-Zigzag-Level-Order-Traversal/

Difficulty : MediumType: Tree, BFSLanguage : Java Clarification 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

https://leo-yang0201.github.io/leo-yang0201.github.io/2019/12/17/Leetcode-142-Linked-List-Cycle/

Difficulty : MediumType: Linked List && Two PointersLanguage : Java Clarification Given a linked list, determine if it has a cycle in it. Return the node where the cycle begins. Possible Sol

https://leo-yang0201.github.io/leo-yang0201.github.io/2019/12/19/Leetcode-21-Merge-Two-Sorted-lists/

Difficulty : EasyType: Linked ListLanguage : Java Clarification Come up as many solutions as you can. Do it in-place with O(1) extra space Possible Solutions Recursion If one link list is empty, r

https://leo-yang0201.github.io/leo-yang0201.github.io/2020/04/07/Java%E4%BD%8D%E8%BF%90%E7%AE%97%E6%8A%80%E5%B7%A7%E6%95%B4%E7%90%86/

刷题的时候老能看到一些大佬用我看不懂的位运算快速解题，感觉这个位运算自己要是整明白了应该做题能有更大进步，而且位运算较之取余操作是更快的，整理一些常用的位运算技巧和使用场景。 位运算操作符 & 与两个位都是1，结果才为1 | 或两个位都是0，结果才为0 ^ 异或两个位相同时位0，相异为1 ~ 取反0变1，1变0 << 左移各二进位全部左移若干位，高位丢弃，低位补0 >&g

https://leo-yang0201.github.io/leo-yang0201.github.io/2020/03/22/Java%E9%9D%A2%E8%AF%95%E9%A2%98%E6%A8%A1%E5%9D%97%E4%B9%9D/

冒泡排序 算法描述 i从0开始，i与i+1比较，如果i>i + 1，那么就互换 i不断增加，直到i<n - 1（n是数组元素的个数，n - 1是数组最后一个元素），一趟下来，可以让数组元素中最大值排在数组的最后面 冒泡算法优化 如果在某趟排序中没有发生交换位置，那么我们可以认为该数组已经排好序了 代码实现要点 两个for循环，外层控制排序的趟数，内层控制比较的次数，每趟过

https://leo-yang0201.github.io/leo-yang0201.github.io/2020/03/09/Leetcode-121-Best-Time-to-Buy-and-Sell-Stock/

Difficulty : Easy Type: Dynamic Programming Language : Java ClarificationSay you have an array for which the ith element is the price of a given stock on day i. If you were only permitted to complete

https://leo-yang0201.github.io/leo-yang0201.github.io/2020/01/04/Leetcode-155-Min-Stack/

Difficulty : EasyType: StackLanguage : Java Clarification Design a stack that supports push, pop, top, and retrieving the minimum element in constant time. push(x) – Push element x onto stack. pop()

https://leo-yang0201.github.io/leo-yang0201.github.io/2020/03/14/Java%E9%9D%A2%E8%AF%95%E9%A2%98%E6%A8%A1%E5%9D%97%E5%85%AD/

数据库的三范式是什么 第一范式：强调的是列的原子性，数据表的每一列都不可再分 第二范式：要求实体的属性完全依赖于主关键字。不能存在仅依赖主关键字一部分的属性 第三范式：任何非主属性不依赖于其他非主属性，消除传递依赖 数据库的事务隔离级别由低到高依次为 Read uncommitted(读未提交）, Read committed（读提交）, Repeatable read（可重复读）, Seria

https://leo-yang0201.github.io/leo-yang0201.github.io/2020/03/06/%E5%92%8C%E4%B8%BAs%E7%9A%84%E8%BF%9E%E7%BB%AD%E6%AD%A3%E6%95%B0%E5%BA%8F%E5%88%97/

Difficulty : Easy Type: Math, Sliding Window Language : Java Clarification输入一个正整数 target ，输出所有和为 target 的连续正整数序列（至少含有两个数）。 序列内的数字由小到大排列，不同序列按照首个数字从小到大排列。 1 <= target <= 10^5 Possible Solutions 滑

https://leo-yang0201.github.io/leo-yang0201.github.io/2020/03/10/Leetcode-122-Best-Time-to-Buy-and-Sell-Stock-II/

Difficulty : Easy Type: Dynamic Programming, Greedy, Array Language : Java ClarificationSay you have an array for which the ith element is the price of a given stock on day i. Design an algorithm to f

https://leo-yang0201.github.io/leo-yang0201.github.io/tags/

Hi, I use this blog to record my daily practice in computer science and data science.

https://leo-yang0201.github.io/leo-yang0201.github.io/2020/04/07/%E6%8E%A5%E5%8F%A3%E6%B5%8B%E8%AF%95%E9%9D%A2%E8%AF%95%E9%A2%98%E6%B1%87%E6%80%BB/#more

说一下测试流程？ 软件开发完成以后，就会把需求规格说明书、软件程序和源码发过来 项目经理出测试方案（使用什么样的测试方法、测试策略），安全测试计划（测试人员、资源、进度的安排，测试的范围和完成的目标） 测试人员编写和执行测试用例 提交缺陷并且进行跟踪 编写测试报告

https://leo-yang0201.github.io/leo-yang0201.github.io/2019/12/16/Leetcode-283-Move-Zeroes/

Difficulty : EasyType: Array && Two pointersLanguage : Java Clarification Move all 0’s to the end of the array You must do this in-place without making a copy of the arrayMinimize the total n

https://leo-yang0201.github.io/leo-yang0201.github.io/2020/03/11/Leetcode-198-House-Robber/

Difficulty : Easy Type: Dynamic Programming Language : Java ClarificationYou are a professional robber planning to rob houses along a street. Each house has a certain amount of money stashed, the only

https://leo-yang0201.github.io/leo-yang0201.github.io/2020/03/04/%E5%AD%97%E8%8A%82%E8%B7%B3%E5%8A%A8%E5%90%8E%E7%AB%AF%E9%9D%A2%E8%AF%95-%E8%81%AA%E6%98%8E%E7%9A%84%E7%BC%96%E8%BE%91/

Type: ArrayLanguage : Java Clarification 牛客网链接​ 我叫王大锤，是一家出版社的编辑。我负责校对投稿来的英文稿件，这份工作非常烦人，因为每天都要去修正无数的拼写错误。但是

https://leo-yang0201.github.io/leo-yang0201.github.io/2020/03/25/Leetcode-200-Number-of-Islands/

Difficulty : Medium Type: DFS,BFS,Union Find Language : Java ClarificationGiven a 2d grid map of '1's (land) and '0's (water), count the number of islands. An island is surrounded by w

https://leo-yang0201.github.io/leo-yang0201.github.io/2020/03/03/Leetcode-82-remove-duplicates-from-sorted-list-ii/

Difficulty : MediumType: LinkedListLanguage : Java Clarification Given a sorted linked list, delete all nodes that have duplicate numbers, leaving only distinct numbers from the original list. Possi

https://leo-yang0201.github.io/leo-yang0201.github.io/2020/03/06/Java%E9%9D%A2%E8%AF%95%E9%A2%98%E6%A8%A1%E5%9D%97%E4%BA%8C/

Java容器都有哪些？常见容器的目录： Collection和Collections的区别？ java.util.Collection是一个集合接口（集合类的一个顶级接口）。它提供了对集合对象进行基本操作的通用接口方法，Collection接口在Java类库中有很多具体的实现。Collection接口的意义是为各种具体的集合提供统一操作方式，其直接继承接口有List和Set Collection

https://leo-yang0201.github.io/leo-yang0201.github.io/2020/04/09/Leetcode-28-Implement-strStr/

Difficulty : EasyType: Two Pointers,StringLanguage : Java Clarification Implement strStr(). Return the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack. Cl

https://leo-yang0201.github.io/leo-yang0201.github.io/2020/03/26/Leetcode-239-Sliding-Window-Maximum/

Difficulty : Hard Type: Heap,Sliding Window Language : Java Clarification Given an array nums, there is a sliding window of size k which is moving from the very left of the array to the very right. Yo

https://leo-yang0201.github.io/leo-yang0201.github.io/2020/04/02/%E8%85%BE%E8%AE%AF3-31%E5%90%8E%E5%8F%B0%E5%BC%80%E5%8F%91%E4%B8%80%E9%9D%A2%E6%80%BB%E7%BB%93/#more

HTTPS的状态码一般都有哪些？上来第一个问题我就给忘了，脑子里全部都是404… 常见的HTTP状态码： 200：请求成功 301：永久重定向 404: 客户端请求的语法错误，服务器无法理解 500: 服务器端在执行时发生错误，无法完成请求

https://leo-yang0201.github.io/leo-yang0201.github.io/2019/12/17/Leetcode-141-Linked-List-Cycle/

Difficulty : EasyType: Linked List && Two PointersLanguage : Java Clarification Given a linked list, determine if it has a cycle in it. Possible Solutions HashSetIterate all the nodes and

https://leo-yang0201.github.io/leo-yang0201.github.io/2020/02/09/Leetcode-102-Binary-Tree-Level-Order-Traversal/

Difficulty : MediumType: Tree, BFSLanguage : Java Clarification Given a binary tree, return the level order traversal of its nodes’ values. (ie, from left to right, level by level). Possible Solutio

https://leo-yang0201.github.io/leo-yang0201.github.io/2020/03/15/Java%E9%9D%A2%E8%AF%95%E9%A2%98%E6%A8%A1%E5%9D%97%E4%B8%83/

请你简述TCP、UDP的区别TCP和UDP是OSI模型中的运输层中的协议。TCP提供可靠的通信传输，而UDP常被用于让广播和细节控制交给应用的通信传输 TCP面向连接，UDP面向非连接，即发送数据前不需要建立连接 TCP提供可靠的服务（数据传输无差错，不丢失，不重复，按序到达），UDP无法保证可靠交付 TCP面向字节流，UDP面向报文（对实时应用有用如实时视频会议） TCP数据传输慢，UDP数据

https://leo-yang0201.github.io/leo-yang0201.github.io/2020/02/16/Leetcode-64-Minimum-Path-Sum/

Difficulty : MediumType: Dynamic ProgrammingLanguage : Java ClarificationGiven a m x n grid filled with non-negative numbers, find a path from top left to bottom right which minimizes the sum of all n

https://leo-yang0201.github.io/leo-yang0201.github.io/2020/02/10/Leetcode-94-Binary-Tree-Inorder-Traversal/

Difficulty : MediumType: Tree, StackLanguage : Java Clarification Given a binary tree, return the inorder traversal of its nodes’ values. Possible Solutions 递归需要构建一个辅助方法helper，该方法返回类型为空，递归条件是root为

https://leo-yang0201.github.io/leo-yang0201.github.io/2020/03/05/Leetcode-1103-distribute-candies-to-people/

Difficulty : MediumType: LinkedListLanguage : Java Clarification We distribute some number of candies, to a row of n = num_people people in the following way: We then give 1 candy to the first person

https://leo-yang0201.github.io/leo-yang0201.github.io/2020/03/05/%E6%9B%B4%E6%8D%A2Next%E4%B8%BB%E9%A2%98%E5%90%8E%E6%A0%87%E7%AD%BE%E9%A1%B5%E8%B7%AF%E5%BE%84%E5%87%BA%E7%8E%B0%E9%97%AE%E9%A2%98/

最近想给博客上线评论功能，发现之前的huno主题很久没有更新了，不是很方便做评论，就想着把博客改成现在比较常用的Next主题。 但是改完之后发现了一个很要命的bug，所有的html的页面的导航栏的链接都出现了问题，例如点击标签后会直接出现404，原因是URL里莫名其妙多了一个”%20”字符，只要删去就可以访问到页面，我一开始手动修复了一些链接，但目前推测应该是部署到github后，自动加上的这个字

https://leo-yang0201.github.io/leo-yang0201.github.io/2020/03/06/Java%E9%9D%A2%E8%AF%95%E9%A2%98%E6%A8%A1%E5%9D%97%E4%B8%80/

最近陆续的开始投暑期实习简历了，自己也还是没有信心能找到一份Java开发的实习，对面试很恐惧，因为自己不会的实在是太多了。趁着现在这个期中假期，多整理一些Java的面试题目来巩固下基础。 JDK和JRE有什么区别？ JDK : Java Development Kit的简称，是Java开发工具包，提供了Java的开发环境和运行环境 JRE : Java Runtime Environment的简称