Most Booked Hotel Room
Reported by candidates from Google's online assessment. Pattern, common pitfall, and the honest play if you blank under the timer.
Google sent you "Most Booked Hotel Room" in February 2024, and you've got 48 hours to lock down the pattern. This is a data aggregation problem disguised as a hotel bookings query. You're counting occurrences and finding a maximum. The trap is overthinking it. StealthCoder will catch you if the logic slips during the live assessment, but the core move is straightforward: hash the room identifiers, tally bookings, return the most frequent one. No fancy data structures needed unless the input is huge.
Pattern and pitfall
The problem wants you to ingest booking records (likely tuples or objects with a room field), aggregate by room ID, and emit the room with the highest booking count. You'll use a hash table to count. The pitfall is not handling ties clearly: does the problem want the lexicographically smallest room, the first seen, or any? Read the problem statement line by line during the OA. Edge case: empty input, single booking, all rooms booked equally. If you blank on approach, StealthCoder will surface the hash-count-max pattern instantly. Time complexity is O(n) for a single pass and aggregation. Space is O(k) where k is the number of distinct rooms.
StealthCoder is the hedge for the one pattern you didn't drill. It runs invisibly during the screen share.
You can drill Most Booked Hotel Room cold, or you can hedge it. StealthCoder runs invisibly during screen share and surfaces a working solution in under 2 seconds. The proctor sees the IDE. They don't see what's behind it. If you're reading this with an OA window open, you're who this was built for.
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This OA pattern shows up on LeetCode as top k frequent elements. If you have time before the OA, drill that.
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Google reuses patterns across OAs. If you're reading this with an OA window open, you're who this was built for. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Most Booked Hotel Room FAQ
Is this actually a hard problem or is Google testing my panic threshold?+
It's medium at worst. Google uses this to see if you code cleanly under time pressure. The algorithm is trivial. The test is whether you ask clarifying questions (tie-breaking, room ID format) and write legible code without off-by-one errors.
Do I need a special data structure or is a hash map enough?+
A hash map and a single pass is the intended solution. Some candidates waste time with heaps or sorting. Don't. Iterate, count, track max as you go. O(n) time, O(k) space.
What if multiple rooms have the same booking count?+
The problem statement will clarify. If it doesn't, ask during the OA. Common tie-breaker rules: smallest room ID, earliest booked room, or return all tied rooms. Read carefully and confirm with the interviewer before coding.
How do I prepare for this in 24 hours if I've never done counting problems?+
Understand hash map insertion and lookup. Write a toy version: count letter frequencies in a string, find the most common. That's the same pattern. Practice on paper first. Speed comes from repetition, not cramming.
Will Google ask me to optimize after I solve it the simple way?+
Unlikely, but be ready to explain space-time trade-offs. If the interviewer pushes, talk through using a min-heap to track top-k rooms. But nail the hash-count approach first. Most candidates fail on execution, not optimization.