Preface
A 211 traditional engineering master in Zhejiang (yes, mechanical), in order to get a good meal, started all in Java in April last year. In addition to class, the graduate level is basically doing things for the instructor, mainly writing some desktop control software. In my spare time, I also expanded my own web service based on this software, plus a bad street spike, which constituted my resume. 3 items on the list. Since February this year, I have successively voted for some resumes. So far, including the letter of intent, I have taken four offers from Ali, Tencent, Byte, and Meituan.
Face Sutra
Attach some side sutras for reference:
Ali CBU technical department side (38 minutes)
- Self introduction
- Talk about concurrency
- How to solve concurrency (optimistic lock pessimistic lock)
- Talk about optimistic lock and pessimistic lock (mutual exclusion lock, cas)
- Talk about thread pool
- What has juc used (countdownlatch, concurenthashmap)
- Garbage collection talk about algorithms, processes (three algorithms for reachability gcroot)
- Let’s talk about the principle of indexing (three-linked booklet structure)
- Difference between springboot and spring
- What is the difference between nio and netty? What about bio (me???)
- Have you ever used springcloud (no, I have known dubbo)
- What is dubbo used for (?? Service call)
- Are there other middleware learning
- What is the ranking? Are there any awards during postgraduate studies?
- What is this project for
Ali cbu two sides (1 hour 11 minutes)
- How to allocate object memory
- Talk about
- Four kinds of quotes
- threadlocal
- http request process (I didn’t understand what I wanted to ask, I went around for a long time)
- Do you understand single sign-on?
- How does the system perceive
- Do you understand the consistency hash?
- Let's talk
- How to learn
- Are there any online projects (pretend to be)
- Is there any finished product? (No...)
- Dig into the project, dig and cry
- Do you know any new technology?
- Do you write a technical blog
- How to troubleshoot slow service
- Have you checked in the actual project? Are there any impressive bugs?
- Do you have a study plan, and at what stage?
Ali cbu three sides (33 points)
- Self introduction
- Pick a project by yourself (balabalabala)
- netty principle
- Why is netty designed like this
- Dictate the nio multiplexing code
- What is Bloom filter? principle? How is it used in the project
- How to solve the cache avalanche?
- Why multi-level caching?
- Cache database consistency? How to solve it?
- How to implement distributed locks
- How does zookeeper implement distributed locks
- Why can we guarantee successful acquisition
- What is the principle of database index
- Why use b+ tree
- How the index is stored
- How to store the joint index
- Talk about thread status
- What is the difference between wait and block
- Explain idempotence
- Rocketmq transaction message principle, code implementation
- Introduction of tcp protocol
- Three handshake details
- Why is it three times
- The principle of sliding window? How does it work?
Intersection
- Forgot to review it, but it's not difficult. .
- hr just talked and laughed, just tell the truth, hr is all *** lake, you can see when it is installed.
Meituan platform technology side 1 hour
- Self introduction
- Why change career
- 怼Project
- What are the solutions to cache avalanches
- Why use bloom filters, advantages and disadvantages, besides bloom filters, what other solutions are there?
- Why heartbeat, how to realize heartbeat connection, how to understand usability
- What is the difficulty of the project
- Why custom protocols, advantages and disadvantages
- Java runtime area, each function
- Abnormal system, how to understand
- Which versions of the jdk source code have you seen? What impresses 1.7 1.8 besides map?
- The advantages and disadvantages of red-black trees, why not balance trees, where else does jdk use red-black trees
- How many layers will stackoverflow run recursively? ? ?
- Object memory allocation strategy
- Programming questions, traverse once to get all the combinations of a+b=m
- Ask questions
Meituan Two Sides (50 minutes)
- Self introduction
- Where does one’s own advantage lie, let’s give an example
- What computer courses have you studied
- Talk about the operating system, if you design it yourself, what parts are involved
- Process thread difference
- Thread synchronization
- Memory management, why virtual memory
- Does the operating system have a memory size limit? How much memory does 64-bit support)=
- Learn about java multithreading
- Reorder scenes
- How volatile prohibits reordering
- syn and lock, the underlying realization principle of syn
- Hobbies, do you follow any open source projects? Post the blog URL
- Algorithm: n colors, m balls, the order of the balls is fixed, find the shortest left and right index of the sub-array containing all colors, what if you consider end to end connection?
- Rhetorical question
Tencent wxg one hour (hanging)
-
Six-pass algorithm 40 minutes
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Shuffling algorithm: shuffle 52 cards, requiring shuffle as much as possible, and the original cards cannot be repeated in the original position
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Now there are n WeChat groups, and each group contains 2 to m individuals. A data structure is designed to store this information, and the structure is required to quickly find out all the group Ids that each person is in.
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The array a[N] stores the numbers 1 to N-1, one of which is repeated once. Write a function to find the number that is repeated. The time complexity must be O(N), and the space complexity cannot be O[N].
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Now there is a WeChat group with n people in it, and each person’s id is marked with an integer int. Now it is required to find out the person whose id is a symmetric number, such as 3, 121, 12321. Please implement the search function to change the integer to a string for judgment.
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Given a string, such as "1234", please implement a function to convert this string into a decimal integer. System functions cannot be used
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There is a binary tree, and the value of each node is an integer. Write a function to determine whether there is a path from the root to the leaf node in this tree, and the sum of all nodes on this path is a certain value. If exists, return 1, otherwise return 0.
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Talk about design patterns, singletons, factories
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Talk about java polymorphism, how to achieve the bottom layer
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The principle of mysql index, why not use other data structures
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How to verify a custom protocol
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Talk about java from writing code to compiling to running, what does the cpu memory hard disk do? ? ?
Byte beating side (1 hour)
- Self introduction
- sql (a bit simple, forget it)
- Algorithm: Inverse Polish expression (for four operations, find the inverse Polish expression)
- Tell me about what you are studying recently (answer to raft zab)
- Then you can talk about raft, elections, downtime, consistent writing...
- Talk about the token bucket algorithm, how to achieve it
- Cache penetration, cache breakdown, cache avalanche
- How does the message queue ensure reliable delivery
- How to ensure the high availability of the message queue, how to achieve master-slave replication
- Do you understand the database index and how to achieve it
- What are the transaction isolation levels and what is solved
- Talk about Java garbage collection
- G1 and CMS talk about the process, when is the stew
- Rhetorical question
Byte beating on both sides (1 hour)
- Self introduction
- Understand the learning situation, what did you learn
- sql, self-connection is needed. . Not written
- Algorithm: The next arrangement (lc original question, search for the name directly) seconds away
- TCP/IP several layers, three handshake, four waved to talk
- Why TCP is reliable
- How is the TCP timeout retransmission process, and how is the retransmission time calculated?
- Let’s talk about close-wait. If you find that the server has a lot of close-wait, what do you think is the possible reason?
- How does TCP determine the size of each data packet and how to calculate it (I didn't say it well, I said that the better the network, the larger the data packet...)
- Then you talk about TCP congestion control
- Is the microservice learning, how to control the flow, and does the state machine understand?
- Do you understand the distributed consensus algorithm, talk about ZAB, what if the three nodes and the master node are down, and how to ensure data consistency
- Do you know the design pattern, tell me what you are familiar with (strategy, factory, reactor...)
- Operating system process scheduling algorithm
- The principle of database index, how to store the data in the data page
- Why use the auto-increment id primary key? What is the problem if you use business columns such as mobile phone numbers?
- Rhetorical question
Byte beating on three sides (1 hour)
- Self introduction
- I told the interviewer about 3D printing (laughs)
- Dig project
- linux commands (wget scp awk netstat top, etc.)
- Do you understand Domain Driven Design
- Source code seen (JDK, Netty)
- Tell me about the source code you are impressed with in Netty
- sql: Two columns of aid bid in table a, bid and bid foreign keys in table b, find out the bid in table b that does not exist in a, the ink will be done
- Algorithm: Tian Ji horse racing, oral thoughts
- How do you understand the design patterns used in the project
- Asked about the internship time
- Rhetorical question
Byte beating hr surface (half an hour)
- Talk and laugh
to sum up
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by themselves. As a developer, not to say that you are required to be the top in the industry, but you must also ensure that you are not eliminated by the market. Learning is the most basic thing for programmers.
