Experience sharing of Sanye's friends: Qianqiu Shu (general manager of Qianqiu)

Write it at the front

I am also a good friend of mine , It's us again LC The administrator of the punch group

Qianqiu's general facial classic was finalized after several times of warming up

Qianqiu is always in our group “ Lying flat circle ” The representative of the , He is low-key, modest and easy to get along with , Welcome to touch

Take this opportunity to , Just opened 「 Friends of Sanya の Experience sharing 」 The column , Let more students learn / Landing experience can be effectively shared , And get to know each other through this column （ Welcome to contribute , Send email ：[email protected] Or wechat ：oaoaya

In general LeetCode Screenshot of personal homepage （https://leetcode.cn/u/chiakimio/）：

Here are Qianqiu Shu （ Always ） The content of ~

Personal background

Some last stream 985, The freshman was brought into the University by a senior at the level of fellow villagers ACM The pit of , Then I was lucky to meet two teammates of my first year and won several awards , Average personal level . The project has only written some simple lesson plans , Basically, I can only CRUD.

Qiu Zhao dared not sneak away because he was refused by the counselor due to school reasons and his advice on asking for leave , So until 9 I went to Huawei for internship in January , Even completely miss Autumn moves （ Don't be like me , It's best to practice in the summer vacation and find a job in the autumn ）.

The preparation time for spring moves is about 2 Months （2 month ~4 month ）, During the interview while learning , Go out to the coffee shop every day with the same roommate who is looking for a job 、 A library or something （ Environment and companionship are really important ）. Because I'm looking for Java Work in direction , During this period, I probably learned JVM、Java Concurrent 、MySQL、Redis、 Network counting 、 Operating system knowledge （JVM Basically not asked ）.

Generally, I just watch online classes & Find a blog & Turn over your face , There is no need to ask what online class is, because a lot of key points can be seen through a search . I will make some notes or outlines , Even reading a blog , Personally, I prefer to knock all the knowledge points along, otherwise I can't remember .

I usually fish , But during the time of looking for a job, I was really studying with high intensity （ About every day 3~5 An algorithm question + Look at the whole day's knowledge , evening 10 I didn't go back until a little later ）.

The eight part essay is very boring , So I just type it or copy it. It's like practicing typing or calligraphy . The algorithm is the accumulation of daily practice , The interview questions are not too difficult, so there is no resistance （ The interview difficulty is about Leetcode Three questions before the weekly competition ）.

Delivery records

• millet （ Hang up the evaluation ）
• JD.COM （ No news ）
• MIHA Tour （ I didn't give an interview after the written examination ）
• Dried small shrimps （ I didn't hang up but I won't arrange a follow-up interview , It is presumed that the delivery is too early + The resume is too bad +hc Insufficient ）
• Ctrip （2 After the noodles offer 了 ）
• NetEase （3 The face feels good , There is no problem with the interviewer's feedback , But still hung up ）
• byte （2 Face to face algorithm problem , Then it was fished 3 There is a problem with the surface mounted operating system , It's almost time for me to graduate from college ）

Comparison of whole dishes , Just take it 1 individual offer. This year, the situation of school recruitment is very serious , If autumn moves can go ashore, don't wait for spring moves . It is suggested that you must decide whether you want to go to graduate school or find a job in the first semester of your junior year , Those who want to find a job should find an internship , Summer internship . Then you can become a full-time employee , You can't become a full-time employee run Autumn recruit , Among the people I know, there are those who have been practicing for half a year .

As for going to Huawei for internship but not delivering , The main reason is that the internship experience is relatively general , I still want to experience the technology direction of the Internet . The humanities are very good , But technically , Huawei's authority is too strict , And the internship Department has no business to do , There is no improvement in personal ability , It's not good for looking for a job later . If you can become a full-time employee, you can still choose , But Huawei has also cancelled becoming a full-time employee .

So those who want to go to the Internet factory should roll up . Of course , According to my friends and classmates around me , Huawei's interview should not be difficult , Instead, the emphasis is on education , And the domestic name is still very loud, which is a good choice .

2022-03-15： Netease has one side 32min

• Self introduction.
• Did you do any projects during your internship ？ Introduce to you .
• The core parameters of thread pool are introduced
• Thread pools execute processes
• Java How locks are implemented
• synchronized Optimization and principle of keywords
• spring How the container handles interface requests
• Which have been used? spring Common comments
• What is an interceptor 、 filter
• IOC、AOP Introduce to you
• I have seen AOP The application of
• Have you ever used log collection ？ such as log4j,sl4j In this way .
• The life cycle of a thread
• MySQL Transaction isolation level for
• InnoDB The default isolation level of
• What is? Next-Key Lock
• What is the leftmost prefix principle
• What happens when the index fails
• SQL sentence ： Query the average scores of students in all courses > 60 Classmate id and Average score
• Users will be in APP Recite words , Design a leaderboard , It can be updated every half an hour , Query the top ten users and the number of words in the day .
• Algorithm problem ：leetcode 103: Zigzag traversal
• ask

* Good experience , The first formal interview was a little nervous , But the questions are basically answered . *

2022-03-16： Ctrip side 55min

• Self introduction.
• Did the project take the initiative to ask the teacher to do
• internship
• How to build the project , There are several pages and functions
• Used to Java Which? Api, What collection classes have you used ？
• ArrayList and LinkedList The difference between
• Which class does the sorting function belong to
• process & The difference between threads
• Thread pool
• Object Class
• What is polymorphism
• The difference between stack and queue
• Stack pop and top The difference between
• left join What do you do?
• sql sentence ： There are multiple groups , Sort by total sales of each group in descending order
• front end js Do you understand the code ？vue Do you know? ？
• Click in the browser url What happened? .
• English level , Do you understand English documents
• spring cloud Let's talk about （ It seems to be a mistake , Thought I had used , But I won't ）
• Java 1.8 What is the default garbage collector
• Algorithm ： Judge whether a binary tree is balanced Leetcode 110： Balanced binary trees
• Design a dining room ordering system , What functions and modules will there be ？
• Chat
• ask

* One side experience is good , I don't know if it's because the group is short of people or something ... *

2022-03-16： Shrimp skin side 49min

• Self introduction.
• Do you know anything about shrimp skin
• Java Garbage collection mechanism
• Java What are the garbage collection algorithms of
• Interprocess communication mode
• The signal and Semaphore The difference between
• 3 The second handshake & 4 The process of waving , How many times can the handshake transmit data
• Is mutual exclusion involved in the project ？（ this 「 Mutually exclusive 」 I didn't understand the meaning ？）
• Lock, understand ？
• Algorithm ：
  • Leetcode 862： And greater than or equal to K The shortest subarray of （ It's good that I did it before. Otherwise, I won't do it for a while ）
  • Leetcode 105： Traversing and restoring a binary tree from preorder and inorder
• ask

* The interviewer's head shines , It looks like a big guy . After introducing himself, he said that he was not very interested in my experience except the competition , So I asked a few random questions without going into depth . Before asking, I also asked if I had actually used , I said no , But I learned , Then he jumped directly and didn't even want to ask . Finally, I lost two algorithm problems. I feel like I want to persuade you to retreat , As a result, I was lucky. Last time I saw someone ask me in Shuiqun, I ran to write it down （ At that time, I won't read the explanation ）, So he got it out . Then he didn't hang up on me , But the evaluation may be poor , In addition, it was delivered early , At that time, the resume was poorly written , Of course, I won't be the first to arrange the interview , In the end, when the enrollment is full, it should be directly postponed to sending a thank-you letter . *

2022-03-22： Netease has two sides 48min

• Self introduction.
• You mentioned Java、Python、C++, How do these three languages import and install packages ？
• Maven do ？ What functions and functions ？
• Introduce the work done during the internship
• How microservices call each other ？
• http and rpc What are the differences and connections ？
• How to use it rpc Of ？
• What is the concept of microservice ？
• The order module needs to have a unique order number , What strategies can be used to generate ？
• There is a user's integral module , How to make a leaderboard function of points ？
• Redis What are the data structures ？
• Redis and MySQL What's the difference? , What scenarios do they apply to ？
• Redis It is read and written through memory , Then if Redis What happens if I hang up ？
• How to guarantee Redis and MySQL Data consistency ？
• MySQL How to guarantee atomicity ？
• Redis Do you support transactions ？
• project Matlab How and Spring Connected ？
• C++ What are the solutions for the code you write Java Do you use it? ？ Or I have one C++ How the project rewrites it into Java Of ？
• Java The project is in Linux and Windows What is the difference between deployment and operation ？ Do you need to make any adjustments ？
• Scene design ： When sending text messages, you need to bring a link to our activities , But the links are very long , I need to do a link compression , Operators give you long links , You provide him with a short link , You already have a very short domain name , How to design such a conversion system ？
• What strategy does a long link map to a short link ？（ Answer string hash ）
• use Java Of hash function ,hash It's a number , Can I use this number directly as the hash value ？
• The hash value is very large , If I take the module directly, there will be hash conflicts , How to solve ？
• Generally speaking, what are the solutions to hash conflicts ？
• Algorithm problem ：「 Put one ipv4 The address is converted to a decimal number 」
• Why do you write two slashes here in your regular expression "s.split(\\.)"？
• If the input is illegal, an exception will appear , Why doesn't it need to be in main Where the declaration will throw an exception ？
• Git What common commands have you used ？
• Why did you use cherry-pick ？ What scene did you use ？
• Say a few linux Common commands of the system and what they do
• Do you understand the container ？（ No, ）
• End directly without asking questions

* Asked a lot of , I think it's OK , In other words, the algorithm problems on both sides of Netease are so simple ？ *

2022-03-28： Two sides of Ctrip 45min

• Self introduction.
• Why didn't you become a regular
• What did the internship do , What has been learned ？
• Have you learned anything technically
• What difficulties have you encountered in your internship
• rewrite Hashcode Method , If I all return 1 What's the problem ？ Yes HashMap What impact will it have ？
• Linked list & The difference between red and black trees ？
• IOC Of bean How to implement the singleton of ？
• How should I get and put instances from a container ？（ What he wanted to ask was something like Hash Table structure design ）
• Unordered array find max, What can you think of ？ What is the complexity ？（ Answer the question directly 、 Stack row 、 Quick line up 、 Merger 、 Bucket row ）
• A string expression , How to calculate the value ？
• Given a function and 5min Let's have a look , Then ask the function function & What are the problems with this thing
  • In writing ：str == "", Should be changed into equals, Then I asked why I used equals
  • The function ： Illegal input is not considered
  • Function naming is not standard
  • Not all parameters are used
  • Constants should be written separately, not directly in numbers
• ask ：
  • What does the business do ？（ I was told by roast that everyone asked me that ）
  • What do I need to improve ？（ Be flexible in your knowledge. Don't learn too much , You can learn more about the framework ）
  • Reading books, online classes and blogs , Is it necessary to read ？

* The interviewer emphasized not to study hard , The key point of learning something is to understand the ideas . *

2022-03-29： Three sides Netease 31min

• Self introduction.
• Introduce the work done during the internship
• Let's introduce the project
• http What are the request headers
• cookie do
• How to implement a login function
• Know what shell command
• How many threads does a process have
• What is multithreading
• Implement a blocking queue ,enQueue and deQueue Two methods （tmd synchronized I can hardly spell it , Why does the keyword system not prompt ）Leetcode 1188. Design finite blocking queue
• Design a function to buy in a puzzle , It is required to design relevant database tables and explain the group opening 、 How to implement the delegation interface
• ask
  • What will be involved in the work ？
  • What do I need to improve ？
  • Watch online classes 、 The blog 、 How to choose the learning methods of reading ？

* The director's face in the email , I thought it was with hr Face to face chatting almost casually , The result is still to ask questions , Wrote a multi-threaded programming , Fortunately, I went to practice before, or I would have to send it . After the interview, I asked him about his evaluation. He said that his skills were not bad , Just lack of experience . Although finally hung up , I don't think so hc Is that right ... *

2022-04-24： Byte flying Book side ：55min

• Self introduction.
• Let's talk about the difference and relationship between processes and threads
• Which resources are thread exclusive
• Let's talk about the principle of process pool
• The way tcp How the agreement works ？ Three handshakes & The process of waving four times
• time-wait What does state do
• url The process of opening a web page
• When the packet arrives inside the server , How the server handles ？
• Do you know about load balancing
• How to handle login information during load balancing ？
• How do you design the login interface
• user token What should I do if I am intercepted and misused by others ？jwt Of token Can it be tampered with ？ What will happen if it is modified ？server How to verify the client ？
• https Do you understand ？
• http Of keep-alive and tcp Of keep-alive What's the difference? ？
• tcp Can live packets of be detected by the application layer ？
• http Request method of ,get & post What's the difference? , Browser or proxy layer pairs get & post There is no need to deal with ？
• get What is idempotent of ？post Can I be idempotent ？
• 64 horse ,8 Track (s) , Before finding out 4, What strategy to adopt & At least a few times ？
• Algorithm problem ：
  • LRU Realization , Added an expiration time , Give priority to eliminating expired data ,get If it expires, it will be returned null（ Just add a judgment , In any case, when the data is full, it will directly kick the chain header department. It will not affect whether it has expired ）
  • Find the maximum width of a binary tree （ Find the layer with the most nodes ）

* The interviewer looks very young , I actually took it offer Ready to swing , But the internship didn't take any action miss 了 , I'm not willing to try the spring moves , I found a big guy to push me . Before the interview, I temporarily sorted out the questions I saw in the byte plane , It turns out that this operation is very useful . *

2022-04-28： Byte flying book two sides ：70min

• Self introduction.
• What did the internship do , What has been learned ？
• Which have been used? git command
• Multithread statistics , Is there any way to solve the concurrency problem ？（ Yes, lock it ,CAS, Then ask if there is any more ？？？ Not anymore ）
• Let's talk about the garbage collection algorithm
• What are the benefits of learning these garbage collection algorithms for you ？
• Based on these recycling algorithms, what can optimize the performance ？ Can I directly operate the garbage collection algorithm ？ Can it be adjusted by external command ？
• What commands do different garbage collectors use to select
• Why recycle by generations ？ Compared to the mark - What are the benefits of clearing ？ When the younger generation recycles, no matter what benefits the older generation has ？
• How to design a thread pool ？
• Why do you need a wired access pool , What are the benefits ？
• Let's talk about 4 Second wave
• Talk about concurrency 、 parallel 、 Asynchronous difference
• Redis What are the data structures
• When a request comes in ,Redis How to find the corresponding data ？
• Redis How to store data in a cluster ？ What should I do to expand the capacity ？（ Send , Didn't learn the distributed part , Can't ）
• Algorithm ：
  • Write a quick line （ It's too long to review and write , You can never remember which sign to write , But I don't want to back the board , Annoyed ）
  • length

  n

  Array of , Divide into

  m

  A subset of , The sum of each subset is required to be equal , For the biggest

  m

  （ Can't , Think about finding the sum of the array , Then enumerate the factors for decomposition , This determines the number of subsets and the sum of each subset . After that, I posted a post for discussion , The sub problem after decomposition becomes Leetcode 698, Write another shape dp Can solve the problem ）

* A quick row is ACMer killer ... If you don't have a clear idea, you must ask about the data range , The data range is easier to use than any hint . Although this question has subsets , But without giving the data range, I still didn't expect to press it at all dp. *

2022-05-07: Byte side 60min

• After the interviewer introduces himself, let me introduce
• Why didn't you go to graduate school
• Are there any other companies
• Is the project curriculum design
• How to achieve single sign on ? Introduce to you jwt Well
• token Will give the client , How did he keep it , How did he bring this with him when he asked token What about ？
• Database paradigm
• The concept and characteristics of database transaction (ACID, Then he said the next isolation level )
• ping What kind of agreement , Which floor ?
• ping How to get the delay of ?
• TCP & UDP The difference between
• Let's talk about TCP Congestion related mechanisms
• linux command : ( Send , Nah )
  • How to see the size of a directory , How to check the disk usage
  • What do you think IO The state of
  • kill Process time , What the process received ? The process is kill What is the specific process of the fall
• Let's talk about AQS Of CLH queue
• Code question ：
  • Write a singleton pattern （ Asked the meaning of each line of code inside , Write more lines notify Found out ）
  • Leetcode 23. Merge K An ascending list

* After hanging up in front, it was fished out a day later , It was said that the team leader felt that his face-to-face comments were not bad. He could give another chance . On the one hand, the interviewer is very kind , I made an error when writing the code. I haven't responded yet. He directly said that you didn't overload the copy constructor . Code 5 min Finished writing . But the overloaded operator is written to the structure , I changed it for half a day lambda I don't know if I made a mistake or c++11 I won't support it delctype That constructor has never been compiled . I have no choice but to reload it honestly cmp The structure gives priority_queue use . Call an overloaded operator bug Writing is longer than writing code logic , It's a dish b 了 ... After turning over the code written before, I made a direct pair , Stupid me ... *

2022-05-11 Byte two sides 48min

• Self introduction.
• Which companies did you meet , Where do you take it offer Do you
• Introduce the garbage collection algorithm
• Introduce to you CMS、G1、ZGC Their characteristics
• G1 All of the Region Are they all the same size
• G1 in , One Region can't let go Object What do I do
• What scenarios are the three recyclers applicable to ？
• Introduce to you ConcurrentHashMap
• The linked list is too long. Why should it be turned into a red black tree , Can I exchange for another tree ？（ The efficiency of adding, deleting and checking is stable ）
• MySQL What are the advantages and disadvantages of the index ？
• How does indexing affect write performance ？
• Why index should be used B+ Trees ？（ The trees are shorter , Low number of layers ）
• If you use other structures ,B+ perhaps Red and black trees All nodes of have been stored in memory , Is there still a gap in performance ？
• understand MySQL Of explain Command ？
• Self increasing id And the only id, Is there any difference in performance ？
• 64 horse ,8 Track (s) , Before finding out 4, What strategy to adopt & At least a few times ？（ Byte always likes to ask this , But this time the question is too old , Especially the 10 And the 11 How did you choose the second time , Why do you have to run that time ）
• Algorithm ：leetcode 64. Minimum path sum , The original array cannot be moved .（ At the beginning, I wrote a

n*m

Spatial , Let me optimize to

O(n)

Space )

• ask

* Finally I met a man who asked me JVM The interviewer of .. The first thing to learn is JVM, Every time, no one asks , be moved .. *

2022-05-19 Byte three sides 47min

• Self introduction.
• What does the internship mainly do ？ What are you responsible for ？ What functions have been developed ？ What did you get .
• Threads & The difference in process
• Does Xie Cheng understand ？
• How the operating system processes are scheduled ？
• Let's talk about virtual addresses and physical addresses
• A program uses more virtual memory than the physical memory of your machine , How to explain ？
• How to maintain page tables ？ Where are they ？（ I don't know ）
• Multiple threads need to modify the same variable , Do you want to lock it , Why lock up ？
• CAS Principle ？
• Do you know the file descriptor ？（ I don't make it ）
• Yes, I have Socket Programming and file manipulation ？（ Nah ）
• Code ：
  • The nearest common ancestor of multiple nodes
  • Leetcode445 The linked list simulates the addition of two numbers
• ask

* The interviewer is very young , But very big guy temperament , It's the way you don't get angry . When I came up, I said that I would not ask what I had asked , Ask about the operating system ... Then I sent it , Operating system learning is poor , hemp .. *

summary

• 22 It's a little difficult to do Spring Festival moves , It's not everywhere hc Or just put it out and it will disappear soon . Personally, it was too late to prepare , I didn't want to find a good place to become a full-time intern , Just to get some internship credits , Huawei asked me, so I didn't invest in other companies . Before my internship, Huawei recruited me in the autumn , And then I'm not going to ask you anything , The two sides directly hung me up and made me feel a little nervous . But the internship experience is good , The Department atmosphere is very harmonious . Unfortunately, Huawei does not have a regular employment mechanism , Although the spring moves can be cast, I don't really want to cast .
• The whole interview experience was fairly normal , All in all, it's about learning things , interview , Then learn while waiting , It's just that it's not easy to interview in the school. It's a bit difficult to find places to interview , Finally, because of the epidemic situation, I had to interview in front of my roommate in the bedroom, which was a little awkward ... Although I am a little afraid of society, I feel that there is nothing to be afraid of when the interviewer begins to ask questions after introducing myself .
• It's a little pity that I didn't input bytes in the internship last year , So when the spring moves, I finally couldn't help but ask the boss for an internal push , Then the Department that started pushing didn't hc 了 , The guy found out and said that he would transfer to flying book . Although it is cold, I have tried it , The spring move is over without regret . Personally, I feel that the department there may be busy , Because the roommate said that the interviewer often cooed or was late when he voted before , Then when I was two, I really googled first ,hr I called to change the time to say that I was in a meeting . Then he was late for the meeting the same day 15min. Hoarse ~, Fear .jpg
• Usually writing questions depends too much on the data range , I can't think of how to write without scope , Especially the optimal complexity

\gt O(n\log{n})

If there is no data range reference at the time of , It is not clear what kind of algorithm is needed . Before Ctrip's written test, if you didn't give the scope, you wouldn't be able to ... Maybe it's just too much food 8..

• Finally, I signed Ctrip （ Because everything else is dead ）, But I think it's already very good , I am very happy to have a result .