reactor是什么？ 有什么作用？请简要描述。 代理模式： ​ 为其他对象提供一种代理以控制对这个对象的访问 单例模式： ​

Reference Enterprise Architecture An overview

业务提供业务方案，用户旅程 BA评估需求，接纳需求，评估工作量，输出US，IT方案 BA向开发进行需求交接 Enterprise life cycle

自我介绍 你好，我是郑烨。感谢您今天抽出时间对我进行面试。我正在寻找一份业务分析工作。首先，我在软件开发方面拥有超过3年的经验，其中，在后端开

Install MongoDB 1 2 3 4 5 6 7 sudo apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv 0C49F3730359A14518585931BC711F9BA15703C6 echo "deb [ arch=amd64,arm64 ] http://repo.mongodb.org/apt/ubuntu xenial/mongodb-org/3.4 multiverse" | sudo tee /etc/apt/sources.list.d/mongodb-org-3.4.list sudo apt-get update sudo apt-get install -y mongodb-org sudo service mongod start 1 sudo nano /etc/systemd/system/mongodb.service 1 2 3 4 5 6 7 8 9 10 [Unit] Description=High-performance, schema-free document-oriented database After=network.target [Service] User=mongodb ExecStart=/usr/bin/mongod --quiet --config /etc/mongod.conf [Install] WantedBy=multi-user.target 1 2 3 4 5 6 7 8 9 10 11 sudo systemctl start mongodb sudo systemctl status mongodb # auto starting MongoDB when the system starts.

简历描述项目的START模型： Situation：规模、功能、目标用户。Task：自己做了什么。Action：自己怎么做的。Result：贡

多路复用，epoll,poll select 遍历整个文件描述符集合 poll 使用链表来表示文件描述符遍历整个文件描述符集合因此没有了监视文件数量的限制 epoll 使用回调

Add Two Numbers 1 2 3 4 5 6 7 8 9 10 11 12 13 ListNode *addTwoNumbers(ListNode *l1, ListNode *l2) { ListNode preHead(0), *p = &preHead; int extra = 0; while (l1 || l2 || extra) { int sum = (l1 ? l1->val : 0) + (l2 ? l2->val : 0) + extra; extra = sum / 10; p->next = new ListNode(sum % 10); p = p->next; l1 =

https://leetcode.com/problemset/top-100-liked-questions/ https://leetcode.com/problemset/top-interview-questions/ https://github.com/mJackie/leetcode https://blog.nowcoder.net/lingo/ https://github.com/afatcoder/LeetcodeTop https://github.com/yuanguangxin/LeetCode/blob/master/Rocket.md solution： https://github.com/doocs/leetcode https://github.com/qinhanmin2014/LeetCode-solutions https://github.com/zzz686970/leetcode-2018 https://github.com/billryan/algorithm-exercise

# Title Difficulty Train of thought 1 Two Sum Easy return indices of the two numbers in an array such that they add up to target. Can we use additional space somehow? Like maybe a hash map to speed up the search? 2 Add Two Numbers Medium two non-empty linked lists stored in reverse order representing two non-negative integers. 3 Longest Substring Without Repeating Characters Medium The reason is that if $s[j]$ have a duplicate in the range $[i, j)$ with index $j’$, we don’t need to increase $i$ little by little.

# Title Difficulty Train of thought 1 Two Sum Easy 2 Add Two Numbers Medium 3 Longest Substring Without Repeating Characters Medium 4 Median of Two Sorted Arrays Hard 5 Longest Palindromic Substring Medium 7 Reverse Integer Easy 8 String to Integer (atoi) Medium 10 Regular Expression Matching Hard 11 Container With Most Water Medium 13 Roman to Integer Easy 14 Longest Common Prefix Easy 15 3Sum Medium 17 Letter Combinations of a Phone Number Medium 19 Remove Nth Node From End of List Medium 20 Valid Parentheses Easy 21 Merge Two Sorted Lists Easy 22 Generate Parentheses Medium 23 Merge k Sorted Lists Hard 26 Remove Duplicates from Sorted Array Easy 28 Implement strStr() Easy 29 Divide Two Integers Medium 33 Search in Rotated Sorted Array Medium 34 Find First and Last Position of Element in Sorted Array Medium 36 Valid Sudoku Medium 38 Count and Say Medium 41 First Missing Positive Hard 42 Trapping Rain Water Hard 44 Wildcard Matching Hard 46 Permutations Medium 48 Rotate Image Medium 49 Group Anagrams Medium 50 Pow(x, n) Medium 53 Maximum Subarray Easy 54 Spiral Matrix Medium 55 Jump Game Medium 56 Merge Intervals Medium 62 Unique Paths Medium 66 Plus One Easy 69 Sqrt(x) Easy 70 Climbing Stairs Easy 73 Set Matrix Zeroes Medium 75 Sort Colors Medium 76 Minimum Window Substring Hard 78 Subsets Medium 79 Word Search Medium 84 Largest Rectangle in Histogram Hard 88 Merge Sorted Array Easy 91 Decode Ways Medium 94 Binary Tree Inorder Traversal Medium 98 Validate Binary Search Tree Medium 101 Symmetric Tree Easy 102 Binary Tree Level Order Traversal Medium 103 Binary Tree Zigzag Level Order Traversal Medium 104 Maximum Depth of Binary Tree Easy 105 Construct Binary Tree from Preorder and Inorder Traversal Medium 108 Convert Sorted Array to Binary Search Tree Easy 116 Populating Next Right Pointers in Each Node Medium 118 Pascal’s Triangle Easy 121 Best Time to Buy and Sell Stock Easy 122 Best Time to Buy and Sell Stock II Easy 124 Binary Tree Maximum Path Sum Hard 125 Valid Palindrome Easy 127 Word Ladder Hard 128 Longest Consecutive Sequence Hard 130 Surrounded Regions Medium 131 Palindrome Partitioning Medium 134 Gas Station Medium 136 Single Number Easy 138 Copy List with Random Pointer Medium 139 Word Break Medium 140 Word Break II Hard 141 Linked List Cycle Easy 146 LRU Cache Medium 148 Sort List Medium 149 Max Points on a Line Hard 150 Evaluate Reverse Polish Notation Medium 152 Maximum Product Subarray Medium 155 Min Stack Easy 160 Intersection of Two Linked Lists Easy 162 Find Peak Element Medium 163 Missing Ranges Easy 166 Fraction to Recurring Decimal Medium 169 Majority Element Easy 171 Excel Sheet Column Number Easy 172 Factorial Trailing Zeroes Easy 179 Largest Number Medium 189 Rotate Array Medium 190 Reverse Bits Easy 191 Number of 1 Bits Easy 198 House Robber Medium 200 Number of Islands Medium 202 Happy Number Easy 204 Count Primes Easy 206 Reverse Linked List Easy 207 Course Schedule Medium 208 Implement Trie (Prefix Tree) Medium 210 Course Schedule II Medium 212 Word Search II Hard 215 Kth Largest Element in an Array Medium 217 Contains Duplicate Easy 218 The Skyline Problem Hard 227 Basic Calculator II Medium 230 Kth Smallest Element in a BST Medium 234 Palindrome Linked List Easy 236 Lowest Common Ancestor of a Binary Tree Medium 237 Delete Node in a Linked List Easy 238 Product of Array Except Self Medium 239 Sliding Window Maximum Hard 240 Search a 2D Matrix II Medium 242 Valid Anagram Easy 251 Flatten 2D Vector Medium 253 Meeting Rooms II Medium 268 Missing Number Easy 269 Alien Dictionary Hard 277 Find the Celebrity Medium 279 Perfect Squares Medium 283 Move Zeroes Easy 285 Inorder Successor in BST Medium 287 Find the Duplicate Number Medium 289 Game of Life Medium 295 Find Median from Data Stream Hard 297 Serialize and Deserialize Binary Tree Hard 300 Longest Increasing Subsequence Medium 308 Range Sum Query 2D - Mutable Hard 315 Count of Smaller Numbers After Self Hard 322 Coin Change Medium 324 Wiggle Sort II Medium 326 Power of Three Easy 328 Odd Even Linked List Medium 329 Longest Increasing Path in a Matrix Hard 334 Increasing Triplet Subsequence Medium 340 Longest Substring with At Most K Distinct Characters Medium 341 Flatten Nested List Iterator Medium 344 Reverse String Easy 347 Top K Frequent Elements Medium 348 Design Tic-Tac-Toe Medium 350 Intersection of Two Arrays II Easy 371 Sum of Two Integers Medium 378 Kth Smallest Element in a Sorted Matrix Medium 380 Insert Delete GetRandom O(1) Medium 384 Shuffle an Array Medium 387 First Unique Character in a String Easy 395 Longest Substring with At Least K Repeating Characters Medium 412 Fizz Buzz Easy 454 4Sum II Medium 1 Two Sum 2 Add Two Numbers 3 Longest Substring Without Repeating Characters 4 Median of Two Sorted Arrays 5 Longest Palindromic Substring 7 Reverse Integer 8 String to Integer (atoi) 10 Regular Expression Matching 11 Container With Most Water 13 Roman to Integer 14 Longest Common Prefix 15 3Sum 17 Letter Combinations of a Phone Number 19 Remove Nth Node From End of List 20 Valid Parentheses 21 Merge Two Sorted Lists 22 Generate Parentheses 23 Merge k Sorted Lists 26 Remove Duplicates from Sorted Array 28 Implement strStr() 29 Divide Two Integers 33 Search in Rotated Sorted Array 34 Find First and Last Position of Element in Sorted Array 36 Valid Sudoku 38 Count and Say 41 First Missing Positive 42 Trapping Rain Water 44 Wildcard Matching 46 Permutations 48 Rotate Image 49 Group Anagrams 50 Pow(x, n) 53 Maximum Subarray 54 Spiral Matrix 55 Jump Game 56 Merge Intervals 62 Unique Paths 66 Plus One 69 Sqrt(x) 70 Climbing Stairs 73 Set Matrix Zeroes 75 Sort Colors 76 Minimum Window Substring 78 Subsets 79 Word Search 84 Largest Rectangle in Histogram 88 Merge Sorted Array 91 Decode Ways 94 Binary Tree Inorder Traversal 98 Validate Binary Search Tree 101 Symmetric Tree 102 Binary Tree Level Order Traversal 103 Binary Tree Zigzag Level Order Traversal 104 Maximum Depth of Binary Tree 105 Construct Binary Tree from Preorder and Inorder Traversal 108 Convert Sorted Array to Binary Search Tree 116 Populating Next Right Pointers in Each Node 118 Pascal’s Triangle 121 Best Time to Buy and Sell Stock 122 Best Time to Buy and Sell Stock II 124 Binary Tree Maximum Path Sum 125 Valid Palindrome 127 Word Ladder 128 Longest Consecutive Sequence 130 Surrounded Regions 131 Palindrome Partitioning 134 Gas Station 136 Single Number 138 Copy List with Random Pointer 139 Word Break 140 Word Break II 141 Linked List Cycle 146 LRU Cache 148 Sort List 149 Max Points on a Line 150 Evaluate Reverse Polish Notation 152 Maximum Product Subarray 155 Min Stack 160 Intersection of Two Linked Lists 162 Find Peak Element 163 Missing Ranges 166 Fraction to Recurring Decimal 169 Majority Element 171 Excel Sheet Column Number 172 Factorial Trailing Zeroes 179 Largest Number 189 Rotate Array 190 Reverse Bits 191 Number of 1 Bits 198 House Robber 200 Number of Islands 202 Happy Number 204 Count Primes 206 Reverse Linked List 207 Course Schedule 208 Implement Trie (Prefix Tree) 210 Course Schedule II 212 Word Search II 215 Kth Largest Element in an Array 217 Contains Duplicate 218 The Skyline Problem 227 Basic Calculator II 230 Kth Smallest Element in a BST 234 Palindrome Linked List 236 Lowest Common Ancestor of a Binary Tree 237 Delete Node in a Linked List 238 Product of Array Except Self 239 Sliding Window Maximum 240 Search a 2D Matrix II 242 Valid Anagram 251 Flatten 2D Vector 253 Meeting Rooms II 268 Missing Number 269 Alien Dictionary 277 Find the Celebrity 279 Perfect Squares 283 Move Zeroes 285 Inorder Successor in BST 287 Find the Duplicate Number 289 Game of Life 295 Find Median from Data Stream 297 Serialize and Deserialize Binary Tree 300 Longest Increasing Subsequence 308 Range Sum Query 2D - Mutable 315 Count of Smaller Numbers After Self 322 Coin Change 324 Wiggle Sort II 326 Power of Three 328 Odd Even Linked List 329 Longest Increasing Path in a Matrix 334 Increasing Triplet Subsequence 340 Longest Substring with At Most K Distinct Characters 341 Flatten Nested List Iterator 344 Reverse String 347 Top K Frequent Elements 348 Design Tic-Tac-Toe 350 Intersection of Two Arrays II 371 Sum of Two Integers 378 Kth Smallest Element in a Sorted Matrix 380 Insert Delete GetRandom O(1) 384 Shuffle an Array 387 First Unique Character in a String 395 Longest Substring with At Least K Repeating Characters 412 Fizz Buzz 454 4Sum II

什么时候用Kafka，什么时候用RabbitMQ？ 使用 Kafka 的场景： 大数据处理： 当需要处理大规模的数据流时，Kafka 是一个很好的选择。它能够高

MySQL Architecture MySQL’s Logical Architecture Transactions mysql事务 mysql隔离级别 Dirty reads(脏读), Nonrepeatable reads, Phantom reads(幻读) Isolation Levels READ UNCOMMITTED READ COMMITTED REPEATABLE READ SERIALIZABLE MySQL’s Storage Engines M

有100个磁盘组成的存储系统，当有3个磁盘同时损坏时，才会发生数据丢失。如果1个磁盘的损坏率是p，请问整个存储系统丢失数据的概率是多少? 在这

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