Lexin interview process

Interview position

Embedded software intern

written examination

The questions are divided into multiple-choice questions and programming questions , Twenty multiple choice questions , Two programming questions ; Multiple choice questions are basically some basic computer knowledge , Relatively simple , It should be easy if you have taken the postgraduate exam , If you haven't taken the postgraduate examination, you may have to review the principle of computer composition a little ; The part of programming problem I do is a problem easy A question medium; The first question is about mathematics , Give a number , The concept of highly synthetic numbers , Please n Number of highly synthetic numbers , I don't know why , I can run by myself , The cattle herding platform shows that the timeout only passes 40%; The second question is about trees , Use recursive methods to solve problems , I don't remember the specific topic , Still have to brush more leetcode, Otherwise, you may not be able to do it when you are nervous .

Technical interview

Duration ：1h40min
First, ask about the project , Just chat , Understand the implementation of some projects , As long as the project is done by yourself , No big problem （30min Less than ？） Then there are some questions c Basic language and operating system （ a key ）
1、volatile The understanding of the （ I may not understand enough , Not enough detail ）
2、 What resources are shared by threads , What resources are unique to you , Is the stack unique to you , How to communicate between processes , Is the stack unique to the process
3、 The structure of the executable file , The function of each zone （ Namely .bss And so on. ）,bss and data What is stored separately , Whether uninitialized and initialized are placed in the same area
4、char array[] = “Hello”; array Where it exists ？hello Where does it exist ？ Are they independent ？
5、sizeof(array) strlen(array) What are the differences
6、 The pointer sizeof How big is it?
7、 Static variables 、 local variable 、 The life cycle of global variables ; Global variables are defined , At which step is it initialized （ What statement does it correspond to ）, Is in main Before or after main after
8、 The process of program loading
9、malloc and new Internal implementation principle , What system calls are used , What is the function name of the specific operation
10、C++ What constructors are there , Tell me the difference
11、 The difference between copy construction and overload equal sign , Then the interviewer gives two pieces of code to ask how many times the constructor is called
12、map Implementation principle of , What's at the bottom
13、 What is the search time complexity of red black tree
14、hashmap The search time complexity 、 Insertion time complexity （ The answer is not sure ）
15、 The search efficiency of red and black trees is higher than hashmap low ？
16、mmap, Understanding of memory mapping

Correct the mistake ：
subject ： Give a piece of code , See what went wrong , I don't remember very specifically , Is to define a string inside the function , Point to the string with a character pointer , Because it's a local variable , So you can't return a local pointer directly .

Tear your hands ：
subject ： Give an unsigned number , Such as 0x1234, Return to shift right n Value after bit , If shift right 4 position , become 0x2341
The subject is very simple ,easy Medium easy, But I didn't think about the boundary very well , Such as n If it is a negative number, etc , And the variables used did not use the interviewer's criteria stdint.h

A small summary ： The basis of the question , Mainly still c And operating systems , The interviewer said there was not enough time , Otherwise, I will ask the computer network , I think if it is cs Coban's , These questions are inevitable （ Or it must be ）, If the undergraduate is electronic like me , You may need to add a lot of operating system knowledge , After all, electronic undergraduate os It's really water class . The other is that the interview intensity is relatively large , full 100 minute , This is the first time I have met for so long , The problem may not be difficult , But it's been a long time , Maybe your reaction speed will slow down , For some unclear and unfamiliar problems , It's likely to be wrong .

HR Noodles

This part is mainly about life 、 hobby 、 Plan your life , Most people don't hang up here . Originally thought HR Face is the last side , later HR say “ If necessary , There will be another round of technical interview ”,OK, So keep waiting

Phone chat

I thought this round was in charge , As a result, a Lexin engineer chatted with me , Inform me that I have passed the interview , Talk to me about what to do in the future , Introduce the specific application scenarios of the business , It's a pleasure , All in all 8 minute . This round is for reference only , My roommate always has the same technical side 3 round , I only have one round , Maybe the situation is different .

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