Booking.com binke Shanghai noodles

origin

A few years , I go to the market for several interviews every year , Learn about the situation of the job market , Discuss the latest technology , Advantages without disadvantages . So I accumulated more facial experience , however booking.com Binke is a special family , Very impressive .
One is timing . At that time, I just came out of Netease , Want to try the opportunity of foreign enterprises , Binke is the first foreign company I met .
The second is the process . Their interview was very rigorous , It's also very human , It has played a great role in my familiarity with the process of foreign enterprises .
Bingke's interview experience has ups and downs , Although I didn't go there in the end , But his interview experience is that I later went to other foreign enterprises and even went abroad , Laid the foundation , So remember in detail .

The process

1. V2EX Forum recommendation

V2EX The forum is a distinctive forum among domestic technology forums , It helped me a lot at that time , Half of the interview opportunities come from the recommendation of strangers , thank senryxie Help recommend to binke , There will be an echo soon , Invite an interview .

2. do hackerrank The subject of （ Be similar to leetcode, But the other side's question is more difficult ）

altogether 4 Avenue , front 2 appear as if leetcode Easy level problem , I spent it. 30 minute

after 2 To be combined with the topic of their business , At least leetcode Difficulty above intermediate , The key is Time is tight ！！ All together 75 minute , Plus the first contact with this form , Time allocation is also unreasonable , As a result, I didn't finish . I'm a little unwilling , Request retry , The reason is that Internet Connection Fail, Newly assigned 4 The difficulty of the question is also the same as last time , result 4 Everything is done , The top 2 Tao completely passed the test , after 2 Some test cases of Tao failed .

To look back , Binke's requirements for coding topics are relatively high , The foreshadowing has been buried here .

3. After May Day HR communicate , among 5.8 Daily journey HR English interview

I remember chatting in English for almost an hour , Tell me about past experience , What I saw and heard in foreign schools before , Planning for future work , And why come to binke . Talk down feeling HR Very professional , Increase the favor of binke .

4. Telephone interview （ Mainly leetcode Similar coding questions ）

5 month 10 Japan booking.com Of charles Code interview , Time complexity O（n）
Feedback afterwards ：

• make clear Good communication in advance , The plan was discussed , It's not going to plunge in ;
• There is the concept of optimization ;
• The concept of time complexity is clear ;
• The problem is that a boundary value modification condition is missing

5. On-site interview

5 month 15 On site interview

booking It is full coding and algorithm and has English ,

• The first is their system design , Design a pop-up system , Inside is the number of bidders who browse the same location and hotel ,

• The second side is fitting, Mentioned inside ab testing,

• The third side is coding, Flow filtration , Because of the problems of boundary condition judgment and time complexity judgment red flag

The next day after the event ,booking Immediately feed back my results , Feedback is fast , This is great

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replay

booking communicate ： System design and fitting It's all over , Especially the system design is very difficult , Because there are many people hanging here , But I mentioned that I rely on Netease tools , Another pair session Do not know much about ;coding Hang up , Communication in the coding process is still good , The handwritten code is also clear and standardized , However, the interviewer did not consider the boundary conditions well in the feedback process , And it is found that there is a dead cycle under specific conditions during the post inspection

I tried to recall that the on-site review did not mention the problem of dead circulation , But with the help of the on-site interviewer , I change the time complexity from O(n square ) Upgrade to O(n) There is . I hurried to find LeetCode A similar question , According to the atmosphere and time requirements of yesterday's interview .

Subject requirements ：

from memory , At that time, the requirement of the topic was to design and implement a core program function of flow control , The core requirement is based on the characteristic value of the web page access request （ such as IP And port ）, Make a sliding time window （ such as 5 minute ） Flow control in , It is required that each characteristic value should not exceed n individual .

My thinking at that time （ There are mainly two data structures ）：

1. The so-called sliding time window , Is to delete the old , New inclusion . So I used a Java Two way queue LinkedList, Expired old access requests , Delete from the queue header ; New requests , Join the end of the queue .

2. The title requires a request for each eigenvalue , Count the number of visits in its time window , So I used it HashMap, The primary key is the characteristic value , The attribute is the number of accesses , Whenever a new request comes in , Will check whether there are expired old requests , Delete ; And new requests , Check whether the number of requests per unit time exceeds the standard according to the characteristic value

Leetcode On similar topics

Today happens to be Leetcode I saw a question on the paper , It's very similar to the interview question , It's just Leetcode The topic is to calculate the average value in the sliding window , The meaning of the question is simpler , Don't need to use HashMap, Use the first data structure LinkedList That's all right. ; Sliding window is length, not time , Relatively simple

Title Description ：346. Moving average in data flow

Given an integer data stream and a window size , Depending on the size of the sliding window , Calculate the moving average of all its integers . Examples are as follows ：

MovingAverage m = new MovingAverage(3);
m.next(1) = 1
m.next(10) = (1 + 10) / 2
m.next(3) = (1 + 10 + 3) / 3
m.next(5) = (10 + 3 + 5) / 3

Because there are ideas after the interview , So this topic is still very easy to do , The implementation code is as follows ：

class MovingAverage {
    

    // This question is similar to what I said in booking.com During the interview 

    Deque<Integer> dq;

    double avg;

    int size; 

    

    /** Initialize your data structure here. */

    public MovingAverage(int size) {
    

        this.dq = new LinkedList<>();

        this.size = size;

        this.avg = 0;

    }

    

    public double next(int val) {
    

        int len = dq.size();

        if (len < size) {
    

            dq.addLast(val);

            avg = (avg*len+val)/(len+1);

        } else {
    

            int rmval = dq.removeFirst();

            dq.addLast(val);

            avg = (avg*len-rmval+val)/len;

        }

        return avg;

    }

}

Actual operation effect ：

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