What the rounds are like
| Stage | What people usually describe |
|---|---|
| Online assessment | HackerRank, usually 3 problems in 90 minutes, easy to medium |
| Technical interview | Live coding with two engineers, usually a medium |
Candidates say problems usually come with a business story attached, so take a moment to work out what's really being asked. Some offices pair with you on a take-home or a small existing app instead, where you explain it, extend it and add tests.
What people have been asked
These come up in candidates' own write-ups of their interviews. We wrote the example prompts ourselves, so the wording you get will be different.
Find peak concurrent reservations
A practice problem: given reservations with check-in and check-out dates, find the busiest moment.
Watch the edges: does someone checking out on a day overlap with someone checking in?
How it might be asked
You're given a list of reservations, each with a check-in and check-out date. Return the largest number of reservations that are active at the same time.
Key concepts to know
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Award top k hotels from reviews
Score each hotel from its review text, where positive words add points and negative ones take them away, then return the top k.
Split and match words cleanly, then don't sort everything when you only need the top few.
How it might be asked
You get lists of positive and negative words, and reviews tagged with a hotel ID. Each positive word in a review is worth 3 points and each negative word -1. Return the k best hotel IDs, highest score first, with ties broken by lower ID.
Key concepts to know
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Rebuild a trip itinerary
Put a traveler's flight tickets back in order as one trip that uses every ticket.
A greedy walk can get stuck at a dead end, so you need a DFS that backs out and tries the next ticket.
How it might be asked
You're given a traveler's flight tickets as from/to airport pairs. Starting from their home airport, put the trip back together in order using every ticket once. If more than one order works, return the alphabetically smallest.
Key concepts to know
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Report from payment and booking logs
Parse JSON logs of bookings and payments and build a report for the payments team.
The first version is easy. The follow-ups add new cases, so keep your code easy to change and know the complexity of each step.
How it might be asked
You get log lines in JSON, some for bookings and some for payments. Produce a report for the payment operations team, such as totals per booking and bookings that aren't fully paid. Then handle the follow-ups the interviewer adds.
Key concepts to know
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How to approach a problem
- Say it back and ask questions. How big is the input? What are the edge cases? What should you return?
- Start with brute force. Say it out loud with its complexity so you've got something to beat.
- Figure out what it really is. Is this secretly a graph? Would sorting help? Do the same subproblems keep coming up?
- Write it and test it. Walk through an example, then try the weird cases.
Key concepts to know
- Heaps and priority queuesAlways have the smallest or largest item ready.
- Hash maps and sliding windowsSwap nested loops for a single pass.
- Graph traversal and shortest pathsBFS, DFS and Dijkstra, and when to use each.
- Binary searchCut the search in half, even when you're searching for an answer.
- Object-oriented designSplit a small program into classes that are easy to change.
- IntervalsMerge, insert and schedule ranges without tripping over the edges.
- BacktrackingTry every option, and stop early on the ones that can't work.
Sources
We pulled this together from candidates' own write-ups of their interviews. They don't always agree, and things change over time.
- Roundz: Booking.com SDE-2 Amsterdam (Jul 2025)
- Jointaro: SWE II Amsterdam (Jul 2024)
- Jointaro: SWE Amsterdam (Jun 2024)
- Jointaro: Software Developer Bengaluru (Feb 2024)
- Jointaro: SWE US (Feb 2025)
- Jointaro: SWE UK (Dec 2024)
- Jointaro: SWE Netherlands (Jul 2025)
- LeetCode Discuss: Award Top K Hotels (Booking OA)
Practice Loop is an independent practice tool and isn't affiliated with or endorsed by Booking.com.