My current status:

YOE: ~ 3.5 in a product-based company
Location: Bangalore, India

Interview Process:

1. OA
2. Recruiter screening
3. 3-4 rounds of interview which includes Algo(maybe one extra round for LLD, subject to team), HLD, Culture fit

• Mode of application: I've applied to multiplie roles(all backend roles aligned to my exp.) on 8th Decemeber 2021 from careers page. Luckily, I got the OA linke the very next day(which should be taken in the next 48 hours).

• OA[90 mins]: (09/12) The assesment was pretty easy. The questions were in the range of easy-medium. Before attempting, I was checking LC's discuss section to undersatnd what questions I can expect. It has three questions:

    	i. find the number of elements with frequency(>2) in an arrray.( all cases passed)
    	ii. String based medium question.(all cases passed)
    	iii. Given positive and negative words, hotels and their reviews, return top K hotel based on the reviews. (frequently asked   question for booking.com) , all test cases passed except one.
    	After completing the OA, I've got a mail on (13/12) and said that, I've passed OA and asked me to schedule intreview with recruiter.
    	

• Recruiter Intreview[45 mins]: (17/12). The recruiter had a thourough discussion about my expreience. There is one catch though, the way an application is processed at Booking.com is different. As I've applied for multiple roles, if any recruiter picks up my application, all other roles which you've applied for will be on-hold. I've applied roles in hotels, fligts, payements and ML. He explained me briefly how exactly each role works. And also gave me the option of choosing between London, Amsterdam and one more europe based location. He also gave me a ballpark figure of CTC based on the location. I've finalised my preference as Software Developer - Data and Machine Learning Platform (DMLP) at Amsterdam. The overall CTC roughly will be 105 - 110 K EUR. Recruiter wanted to forward my resume to the concerned person who handles DMLP role, but as it was around Christmas and everybody left for the holidays starting next day. I was asked to wait till January 5th 2022 for further process.
  Note: In any europe based locations, they will check with you every single word you've written in your resume. Booking.com's London fixed pay is slight high(coz of the high cost-of living in UK) than Amsterdam, but there is no stock option in UK.

• 1st round(DSA)[60 mins]: (07/01). There were 2 Tech leads who are condncting my interview. I was asked to solve 1 question to solve in this round. It was conducted on hackerrank codepair.

  Question: We noticed that after a few years in production our file storage started taking too space. Luckily for us, we identified a high percent of identical files and folders in the storage and decided to compact it. As a solution we decided to find all identical folder structures, deduplicate and create symbolic links to the only copy.
  We follow the next principle: 2 folders are identical if they contain an identical set of files and subfolders. 2 files are identical if they have the same name.

\
|—— bar
|    |—— baz
|    |  |—— boo
|    |  |      |—— a
|    |  |      |—— b
|    |  |—— c
|    |—— fizz
|    |  |—— buzz
|               |—— a
|               |—— b
|—— foo
|    |—— boo
     |        |—— a
     |        |—— b
     |——c

In the example above folder bar/baz/boo is identical to bar/fizz/buzz and foo/boo; also bar/baz is identical to foo. (and few other combinations like boo and buzz are also identical). I was expected to write the core logic in good bug-free code.

The weird part is all I was given to input fucntion was just the root as a string. I've faced a problem in how to dig down into folders and how to keep track of how deep I'm going into the functions. Interviewer suggested to use file.io in java, I said I'm not really familiar in using that package. Then they came up with imaginary functions like:

1. isFile, isFolder which will tell me if the current elemnt is a folder/file.
2. getFolderContents: will get you folder's contents in a string sepereated by commas.

30 mins passed by, the interviewers now just want to me to list out the identical files first. Then I've started writing the code in a recursive(tail) manner and did couple of dry runs. The interviewrs seemed satisfied by this solution, although I might have solved only 40-50% of the original problem.

All in all, I wasn't prepared for algo, I want to understand how does international job applications work in brief. Booking.com's interviews should be doable and are mostly of the range medium and Amsterdam is a beautiful city to live in.

Thanks for reading. Good luck!