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Amazon interview notes, page 49 of 159

FAANG / Big Tech

Most of these Amazon write-ups come from Software Engineers (1,092), then Data Scientists (182) and Product Managers (165). The most reported rounds are the technical phone screen (618), the behavioral / leadership round (309), the online assessment (228) and the system design round (159).

1581 interview notes · updated Oct 2026

Amazon·Software Engineer·Onsite - Coding / Algorithms

May 2026
Amazon SWE interview with an array simulation problem that looks deceptively simple until you actually try to count passes efficiently. Pretty classic Amazon coding round vibe.
  • Given an array that is a permutation of 1 through n, you scan left-to-right looking for consecutive integers starting from 1. Each time you find the current target you increment it and keep going in the same pass. When you hit the end, if you haven't found everything yet, you restart from the beginning. How many full passes does it take to find all n numbers?

“My first instinct was to just simulate it, and that works fine for small inputs, but I had a feeling they wanted something better.”

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Amazon·Data Scientist·Technical Phone Screen

May 2026
Amazon data scientist interview that went deep into stats and experiment design. Four connected sub-problems built on each other, which I didn't expect, and the clustering question at the end nearly broke me.
  • Given a baseline conversion rate estimated from 100,000 users, compute a 95% Wald confidence interval and then a Wilson or Agresti-Coull interval. Why might the latter two be preferable?
  • Using a normal approximation for two proportions, derive the per-variant sample size needed to detect a 5% relative lift at 80% power and a two-sided alpha of 0.05. State your assumptions explicitly.
  • If you're simultaneously testing three metrics in an experiment, how do you apply a Bonferroni or Holm correction? What's the adjusted significance threshold, and how does that compare to controlling the false discovery rate with Benjamini-Hochberg?
  • Your experiment data has user-level clustering because users visit multiple times. Why does this violate the independence assumption, and how do you correct for it? What happens to your power estimates?

“I knew the Wald formula cold but fumbled the explanation of why it breaks down near the boundaries.”

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Amazon·Software Engineer·Technical Phone Screen

May 2026
Amazon SWE interview with a classic LRU cache design question. The scope kept expanding as the conversation went on, which I wasn't fully ready for.
  • Design and implement a fixed-capacity cache with get and put operations running in O(1) average time, evicting the least recently used entry when full. Cover how recency gets updated, how duplicate keys are handled, what get returns on a miss, and walk through thread-safety and testing considerations.

“Started fine with the hashmap plus doubly linked list approach, moved the accessed node to the front on both get and put, returned -1 for missing keys.”

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Amazon·Software Engineer·Onsite - Behavioral / Leadership

May 2026
Amazon behavioral round for a software engineer role. One question, but it had a lot of layers to it and I felt like I was still answering it when they cut me off.
  • Tell me about a time you had to make a difficult trade-off under time pressure. What options did you consider, how did you communicate the risks to stakeholders, what did you ultimately decide, and how did you measure whether it worked? Looking back, what would you do differently?

“This question is sneaky because it's actually four questions stitched together and if you don't pace yourself you'll spend six minutes on the setup and have nothing left for the measurement part.”

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Amazon·Software Engineer·Hiring Manager Screen

May 2026
Interviewed for a business analyst role at Amazon. One question, pretty open-ended, and I'm still not totally sure I answered it the way they wanted.
  • How do you translate analytical findings into concrete business decisions or actions?

“I rambled a bit here.”

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Amazon·Software Engineer·Onsite - Coding / Algorithms

May 2026
Amazon SWE coding round, got a Morse code decoding problem that looked deceptively manageable until the 'no character separator' part hit. The whole thing was about enumerating all valid partitions per word segment and combining them across words.
  • Given a Morse code string split into word segments by a known separator, decode all possible sentences. Within each word segment there are no character separators, so you need to find every valid way to partition each segment into valid Morse tokens, then combine across words to return all unique decoded sentences.

“My first instinct was a simple recursive split and I got the basic case working fast.”

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Amazon·Software Engineer·Online Assessment (OA)

May 2026
Amazon SWE coding round, one problem the whole time: level-order traversal with per-level averages. Pretty standard BFS stuff but the I/O parsing tripped me up more than the actual algorithm.
  • Given a binary tree as a level-order array (with nulls for missing children), compute the average value of nodes at each level and print them space-separated from root to deepest level.

“BFS was the obvious move and I got there, but I wasted probably 10 minutes fumbling with parsing the input string into an actual tree.”

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Amazon·Software Engineer·Onsite - System Design / Architecture

May 2026
Amazon software engineering interview that went deep on infrastructure and architecture topics. Five distinct technical areas back to back, no behavioral questions at all, which I honestly wasn't expecting.
  • Design a multi-layer VPC architecture with public, private, and management network segments. Walk through how you'd handle routing between layers, and how subnets, route tables, and security groups enforce isolation.
  • For a fleet of 2,000 servers, how would you plan CIDR block allocations across subnets, accounting for AWS reserved addresses and room to grow?
  • How would you centrally manage a mixed fleet of Linux and Windows instances, covering configuration management, patching, access control, and inventory?
  • Recommend a shared storage solution for concurrent access across many servers. Compare NFS-style, SMB-style, and any alternatives on performance, consistency, and cost.
  • Design a single sign-on system where users authenticate once to access multiple services. Cover identity provider selection, how trust relationships work, and the token flow.

“This is the kind of question where I talk too much upfront and then run out of time on the security group specifics.”

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Amazon·Software Engineer·Technical Phone Screen

May 2026
Amazon SWE round focused entirely on tree serialization and deserialization. Pretty involved question with a lot of back-and-forth on design choices, complexity, and edge cases throughout. Not the kind of round where you just code quietly and move on.
  • Design an algorithm to serialize a binary tree into a string and deserialize it back to the original structure. Your encoding format is up to you, but the round-trip must reconstruct the tree exactly.

“I went with preorder traversal and null markers, which felt safe.”

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Amazon·Machine Learning Engineer·Technical Phone Screen

May 2026
Amazon ML engineering interview, one question about production deployment experience. Pretty technical but framed behaviorally, which threw me a bit.
  • Walk me through a time you took a machine learning model from development into production. What did the integration look like and what tools were involved?

“Spent the first minute rambling about model accuracy before realizing they clearly wanted infra details.”

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