NURO·Software Engineer·Technical Phone Screen·Intermediate

IntermediatePrefer not to say

May 2026Remote

Summary

Nuro coding screen, one question the whole time. It's a merge intervals variant but flipped: find the gaps instead of the merged chunks. Felt straightforward once I saw it but I definitely over-thought the setup before realizing it was just a sweep.

Questions Asked (1)

Given a list of intervals, return all the gaps between them: the maximal ranges on the number line not covered by any input interval.

Algorithms & Data Structures

Author's notes

I recognized the merge intervals pattern pretty fast, which actually slowed me down a bit because I kept second-guessing whether they wanted something fancier.

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AI HintsAI Generated

Suggested Approach

First, clarify the definition of gaps and edge cases like overlapping intervals, touching intervals, and infinite gaps. Then, propose sorting the intervals by start time and merging them to identify uncovered ranges. Finally, iterate through the merged intervals to collect gaps between them, handling boundaries appropriately.

Pro tip: Explicitly discuss how you handle intervals that just touch (e.g., [1,2] and [2,3])—whether they create a zero-length gap or no gap—and mention that gaps can be unbounded on the ends if the problem allows.

1. Clarify requirements and edge cases

Ask whether intervals are closed/open, if gaps can be infinite, and how to treat touching intervals. Confirm output format and whether intervals are sorted.

2. Sort intervals by start

Sort the input intervals by their start value to enable linear merging. This is crucial for O(n log n) efficiency.

3. Merge overlapping intervals

Iterate through sorted intervals, merging any that overlap or touch (depending on definition). Keep track of the current merged interval's end.

4. Collect gaps between merged intervals

After merging, iterate through the merged list and for each consecutive pair, if the next start is greater than the previous end, record the gap (prev.end, next.start).

5. Handle boundaries and return result

If infinite gaps are allowed, include (-inf, first.start) and (last.end, +inf). Otherwise, only return finite gaps. Return the list of gaps.

Key Points to Mention

Time complexity: O(n log n) due to sorting, with O(n) for merging and gap collection.
Space complexity: O(n) for storing merged intervals and gaps.
Edge cases: empty input, single interval, all intervals overlapping, intervals that touch, and infinite gaps.
Definition of gap: whether endpoints are inclusive/exclusive and if zero-length gaps count.
Handling of unsorted input and the need to sort first.
Potential follow-up: how to handle streaming intervals or very large datasets.

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.