Amazon Interview Questions — Page 129

Amazon·Software Engineer·Technical Phone Screen

Jun 2026

Amazon SWE interview that was basically a Pandas deep-dive. Five interconnected sub-problems on a single DataFrame, all requiring vectorized solutions. No behavioral, no system design, just time-series wrangling under pressure.

Given a DataFrame with columns user_id, event_type, ts_utc, and revenue, parse ts_utc as a timezone-aware timestamp and convert it to America/Los_Angeles while correctly handling DST transitions.
Using the same DataFrame, compute daily active users and then apply a 7-day moving average over that DAU series.
For each combination of user and event_type, compute a 7-day rolling count of events without using any explicit Python loops.
Compute weekly user retention: for each week w, find how many users who were active in week w also appear in week w+1, and express that as both a count and a rate.
After all the aggregations, resample the resulting time series to fill in any missing calendar dates with zeros rather than NaN.

“I knew the broad strokes but fumbled the exact Pandas call for ambiguous times during the fall-back hour.”

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Amazon·Software Engineer·Onsite - System Design / Architecture

Jun 2026

System design round at Amazon for a software engineering role. The whole session was basically one big problem about pickup point recommendations in a ride-hailing context, with a bunch of follow-ups layered on top. Felt more open-ended than I expected.

Design an algorithm and high-level system for recommending a pickup point in a ride-hailing app, where the passenger's location may be imprecise and the driver needs a safe, legal place to stop.
How would you handle pickup point recommendations in constrained environments like airports or shopping malls?
How would you use historical trip data to improve pickup point recommendations over time?
How would you adapt the system for passengers with limited mobility or who cannot walk far?
What metrics would you use to A/B test changes to the pickup recommendation algorithm?

“This one took me a minute to even scope properly.”

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Amazon·Software Engineer·Online Assessment (OA)

Jun 2026

Amazon OA for a full-stack role, debugging a broken Node.js/Express/MongoDB backend for a movie review platform. No greenfield coding, just tracing and fixing logic spread across controllers, middleware, and utilities. Trickier than it sounds.

A review moderation system needs to permanently flag users after 3 consecutive violations, both during review creation and during review updates. The existing code handles these flows separately and inconsistently. Find and fix the bugs.
The moderation system also needs to flag users after 3 cumulative violations across both create and update operations combined, not just consecutive ones within a single flow. Debug why cumulative tracking is broken.
Rate limiting should block users after 4 review operations within a 60-second window, counting both POST and PUT requests together. The current implementation tracks them separately. Fix it.
The system should block review creation and review updates if the content contains inappropriate language. Both flows are broken. Debug and fix the content moderation checks.

“This is where I lost the most time.”

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Amazon·Software Engineer·Technical Phone Screen

Jun 2026

Amazon SWE interview with two algorithm-heavy problems back to back. Both required solid knowledge of advanced data structures and dynamic programming under time constraints. Left feeling like I probably over-explained part A and rushed part B.

Given an integer k and an array of length n, compute the median of every contiguous subarray of length k (using the lower median for even k), then return the maximum and minimum of all those medians. Your solution must run in O(n log k) time and O(k) space. Describe the data structures you'd use.
You have a binary array of length n. You can flip any bits. After flipping, the array must be partitionable into contiguous segments where each segment has even length and all identical values. Minimize the number of segments first, then minimize total flips as a tiebreaker. What's your algorithm and its complexity?

“I knew immediately this was a two-heap setup, but the part that tripped me up was maintaining balance while sliding the window.”

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Amazon·Software Engineer·Online Assessment (OA)

Jun 2026

Amazon OA for a SWE role. One algorithmic problem, cycle graph shortest path with multiple queries. Pretty standard competitive programming territory but the constraint sizes mean you can't brute force it.

You have a circular array of N nodes where each element represents the clockwise distance to the next node. Given Q queries each with two nodes, find the shortest path between them along the cycle (clockwise or counterclockwise) and return the total sum across all queries.

“The core idea isn't hard once you see it: precompute prefix sums of the distances, then for any pair the clockwise distance is just a prefix difference, and counterclockwise is total minus that.”

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Amazon·Software Engineer·Technical Phone Screen

Jun 2026

Amazon SWE coding round, one question the whole time. Pretty classic in-place merge problem but with a descending twist that tripped me up more than I expected.

Given two descending-sorted arrays, merge the second into the first in place so the result is also sorted in descending order. The first array has enough extra capacity to hold both.

“I knew two pointers immediately but my brain kept defaulting to the ascending version I'd drilled a hundred times.”

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Amazon·Data Scientist·Onsite - System Design / Architecture

Jun 2026

Amazon Data Scientist system design round, one big open-ended question about building a recommendation system from scratch. The scope was pretty wide and I kept second-guessing how deep to go on each piece.

Walk through the design of a full recommendation system: data collection, feature pipelines, training workflow, how often you refresh the model, the online vs offline architecture split, and how you'd hit real-time latency targets. Also address feedback loops, A/B testing, and what happens when the model fails.

“This question ate up basically the whole session.”

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Amazon·Software Engineer·Online Assessment (OA)

Jun 2026

Amazon SWE online assessment with an interval merging problem that looks straightforward but has a few edge cases that'll trip you up if you're not careful.

Given a list of delivery zones represented as intervals, and a maximum length k, add exactly one new interval of length at most k to minimize the number of disconnected groups (connected components) in the resulting set of intervals.

“Spent the first ten minutes just staring at this.”

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Amazon·Software Engineer·Onsite - System Design / Architecture

Jun 2026

System design round at Amazon for a software engineer role. The whole session was basically one big parking lot question that kept expanding the more you answered it.

Design a parking lot system that handles multiple vehicle types, multiple levels, entry and exit gates, ticketing, payments, and availability tracking with hourly and daily pricing rules. Define the core classes, their relationships, and APIs for parking, unparking, and querying availability.
How would you handle concurrency and data consistency when multiple vehicles try to claim the same parking spot at the same time?
What happens when the parking lot is at full capacity? Walk through how your system handles that scenario.
How would your system handle failure scenarios like a lost or damaged parking ticket?

“I started with the class structure which felt okay, Vehicle as a base with subclasses, Ticket tied to a ParkingSpot, that kind of thing.”

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Amazon·Software Engineer·Onsite - Behavioral / Leadership

Jun 2026

Amazon SWE behavioral round, just one question but they really sat in it for a while. Pretty standard leadership principle territory but the follow-ups had some bite.

Tell me about a time you went beyond your assigned responsibilities. What was the situation, what motivated you, what did you actually do, and what came out of it for you, your team, and the project?

“The four-part structure of this question is kind of a trap in itself because you think you can just tell a linear story and be done, but they kept asking 'and what motivated you specifically' like they weren't satisfied with 'I saw a gap and filled it.' I stumbled on the motivation part.”

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