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Merge Intervals at Stripe — Interview Guide

How to approach Merge Intervals in a Stripe interview: the optimal approach, what Stripe interviewers look for, and company-specific tips.

Updated 2026-09MediumIntervals

The problem at Stripe

Given a list of intervals [start, end], merge all overlapping intervals and return the non-overlapping set that covers the same ranges.

Stripe uses this problem to assess apis, money, and pragmatic engineering. Expect Stripe-specific follow-ups that tie the solution back to production reasoning and the company's engineering bar.

Key concepts

Sorting by start time turns a pairwise problem into a single linear sweep.
Two intervals overlap when the next start is ≤ the current end.
Merge by extending the current end to the max of the two ends.

Approach

Sort intervals by start time.
Initialize the result with the first interval.
For each next interval, if it overlaps the last result interval, merge; otherwise append.

def merge(intervals):
    intervals.sort()
    merged = [intervals[0]]
    for s, e in intervals[1:]:
        ls, le = merged[-1]
        if s <= le:
            merged[-1][1] = max(le, e)
        else:
            merged.append([s, e])
    return merged

Complexity

Metric	Value
Time	O(n log n) (the sort)
Space	O(n)

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