There were total 5 rounds.

Hackerrank test

1. Extend a half implemented Spring boot application
   1. Application contains data about hotels and cities.
   2. Need to implement few APIs related to finding nearest hotels to the city center
   3. There were some pre-written test cases, which deliberately written to fail the build, need to fix them and add few more if time permits.

I was able to implement all the APIs asked and add couple of test cases and build the failed test cases, but I'm told I just made it to the final interviews with some 40% score.

Coding test
There were two questions

1. Given a string "ABC#DD#E", for every # consider it as a back space. Output the final string. For example, in the above string answer will be "ABDE". SImilary "A##BB#E##F" will output "F" (Use stack)
   1. This was extended saying if you see @ consider it as a redo, how do you implement it. For example, A#@BB#E#F will output "ABF"
2. Given a stream of rows in the following format, find the cities which has 3 or more hotels with same name
   hotelId, hotel Name, City Name

Final Interviews:

Coding Round

1. Given a list of flights between destinations something of the following order: (Following table is not exact in the question, I don't remember the exact figures, this is to just explain the format)
   1. Amsterdam -> Paris on August 10, Price - 300 euros
   2. London -> Paris on August 15, Price - 410 euros
   3. Paris -> London on August 13, Price - 300 euros
   4. London -> Amsterdam on August 17, Price - 400 euros

Hotel cost per night:

1. Amsterdam - 400 euros
2. Paris - 500 euros
3. London - 300 euros

Find the longest itinerary possible (in terms of the duration) given a upper cap on the budget, say 5000 euros.

(You need to use DFS, I explained them the solution, but was too tired that day so couldn't implement it properly)

Design round

1. Design a view counter service which shows the number of current viewers viewing the product page on Booking.com.
2. I explained them the components and how to scale the service using Redis and queues
   I realised I stammered a lot throughout the interview due to lack of confidence, which confused the interviewers totally.

Culture Fit

1. Typical fit questions like what are the situations when you showed leadership skills
2. Were there any conflicts between peers, if so how did you react to them

Except for culture fit, all rounds were taken by two interviewers.

Overall, it was good experience interviewing with Booking.com. Amsterdam is an excellent place to move to, I wish I could have been more attentive and focussed during the interview hours. Interview is not so tough, but not so easy as well. With good preparation anyone can crack it. I will try once the cool down period completes. Hope at least one from LC community is benefitted from my experience and crack the interview, good luck :)