Range Module
A hard-tier problem at 44% community acceptance, tagged with Design, Segment Tree, Ordered Set. Reported in interviews at Machine Zone and 2 others.
Range Module is a hard design problem that shows up in Google, Coupang, and Machine Zone interviews. You're building a data structure that tracks which ranges are covered and supports adding ranges, querying coverage, and removing ranges on the fly. The 44% acceptance rate reflects how brutal the implementation details are. Most candidates either nail the approach or get tripped up by interval merging logic and boundary conditions. If this hits your live assessment and you blank on the merge strategy, StealthCoder surfaces a working solution in seconds, invisible to the proctor.
Companies that ask "Range Module"
Range Module is the kind of problem that decides whether you pass. StealthCoder reads the problem on screen and surfaces a working solution in under 2 seconds. Invisible to screen share. The proctor sees nothing. Built by an engineer who got tired of watching his cohort grind for six months and still get filtered at the OA stage.
Get StealthCoderThe trap here is thinking simple. A naive list of intervals breaks fast under repeated insertions and deletions. The real skill is recognizing this needs an ordered data structure (segment tree or a clever use of a sorted set) to keep intervals non-overlapping and mergeable. The algorithmic complexity lives in three operations: add a range (merge overlapping intervals), remove a range (split intervals), and query (binary search the sorted structure). Most candidates build the first operation fine, then struggle when a removal must split an existing interval in two. Boundary conditions around inclusive/exclusive endpoints trip up everyone. StealthCoder is the hedge when the interview pivots to a variant you didn't prep.
Pattern tags
You know the problem.
Make sure you actually pass it.
Range Module recycles across companies for a reason. It's hard-tier, and most candidates blank under the timer. StealthCoder is the hedge: an AI overlay invisible during screen share. It reads the problem and surfaces a working solution in under 2 seconds. Built by an engineer who got tired of watching his cohort grind for six months and still get filtered at the OA stage. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Range Module interview FAQ
How hard is Range Module really for FAANG prep?+
It's legitimately hard. At 44% acceptance, you're competing against candidates who've seen segment trees or interval problems before. Google and Coupang use it to test whether you can design under pressure, not just code. If intervals are weak for you, this becomes a tier-one priority.
What's the most common mistake candidates make?+
Forgetting to merge overlapping intervals after an add operation, or failing to handle the case where a removal splits an interval into two separate ranges. Both require careful iteration and boundary logic. Most people code one operation cleanly, then rush the others.
Do I need a segment tree for this?+
No, but it helps if you know one. A sorted list (or ordered set) with careful interval merging and splitting works just as well and is often simpler to debug live. The key is keeping intervals non-overlapping and sorted at all times.
How does Range Module relate to the Design and Ordered Set topics?+
Design tests your ability to choose the right data structure and trade off time/space. Ordered Set is the implementation detail that makes queries and insertions efficient. You need both to solve it fast under interview pressure.
Is this still asked at Google and Coupang?+
Yes. Interval problems stay in rotation at both companies. The variant might change (add/remove/query patterns differ), but the core skill of managing overlapping ranges is evergreen in systems and backend interviews.
Want the actual problem statement? View "Range Module" on LeetCode →