120 questions · from 35 interviews · 1 asked more than once
Interview Experience interview questions
Every question candidates reported from their Interview Experience interviews, most frequently asked first. Each links to the write-up it came from, so you can see the round and how it went.
Interview Experience coding and DSA questions
- 01
Kth Smallest Element in a BST
Kth Smallest Element in a BST
Asked 2 times · From This is a Google OA question — don’t miss this opportunity
- 02
Maximum Subarray Sum for Range Queries
Given an array A of size N and M queries (li, ri). For each query return the maximum subarray sum that lies completely within the segment [li, ri]. Constraints: 1 ≤ N ≤ 50000, -15000 ≤ A[i] ≤ 15000, 1 ≤ M ≤ 50000, 1 ≤ li ≤ ri ≤ N.
- 03
Count Substrings with One Swap Allowed
Given a string S of length N and a pattern U of length M (M ≤ N). Count the number of substrings of S that match U either exactly or after swapping any two consecutive characters in the substring. Example: S = "abcacbabc", U = "abc" → matches are "abc",…
- 04
Minimum Cold Starts for Service Dependency Graph
A microservice platform has N services numbered 1..N. Some services depend on others (directed edges). If service B is started, any service A that depends on B starts automatically. Services with no dependencies cannot start on their own, but any service can…
- 05
Maximum Subarray Sum with Opening and Closing Windows
Given an array A of size N representing daily profit/loss, and M queries each defined by four indices (x1, y1, x2, y2). The opening day i must satisfy x1 ≤ i ≤ y1, the closing day j must satisfy x2 ≤ j ≤ y2, and i ≤ j. For each query return the maximum…
- 06
Time Based Key-Value Store
Design a data structure that supports two operations: set(string key, string value, int timestamp) stores the key‑value pair along with the given timestamp. get(string key, int timestamp) returns the value associated with key at the largest timestamp less…
Medium · From Cockroach Labs | MTS | Rejected
- 07
Buy and Sell Stocks with Fixed Transaction Fee
Implement a solution to calculate the maximum profit from buying and selling stocks when each sell operation incurs a fixed transaction fee.
- 08
Construct Binary Tree from Inorder and Level Order Traversals
Given the inorder and level order traversal sequences of a binary tree, reconstruct the original tree.
- 09
Maximum Monsters Defeated with Bullets and Poison
You have a limited number of bullets and poison. Each monster requires a certain number of bullets to defeat and consumes one unit of poison per kill. Determine the maximum number of monsters you can defeat.
- 10
Find Exchange Rate from Currency Map
Given a map containing exchange rates between some currency pairs, compute the exchange rate between two specified currencies if possible.
- 11
Print S‑Style Traversal of an N×N Matrix
Write a program to traverse and print an N×N matrix in an “S” shaped pattern.
- 12
Elevator System (Machine Coding)
Implement core functionality of an elevator control system, handling requests, floor selection, and movement logic.
- 13
Minimum Trips for Contiguous Weights
Given an array of weights and a truck with maximum capacity k. Only contiguous sub‑arrays can be loaded together. Determine the minimum number of trips (or minimum time) required to transport all the weights.
From Amazon SDE1 AUTA Interview Experience — 1.5 YOE | 2024 Batch | July 26
- 14
Min Cost Hospital and Roads
There are n cities and a list of possible roads, each with cost cr. Building a hospital in any city costs ch. Every city must have access to at least one hospital. Find the minimum total cost to satisfy this requirement.
From Amazon SDE1 AUTA Interview Experience — 1.5 YOE | 2024 Batch | July 26
- 15
Maximize Sum of A times Max of B for k Selections
Given two arrays a and b of equal length n and an integer k, select exactly k distinct indices. The score is sum(selected a) max(selected b). Return the maximum possible score.
From Amazon SDE1 AUTA Interview Experience — 1.5 YOE | 2024 Batch | July 26
- 16
Rotten Oranges (Multi‑source BFS)
Given a grid where each cell can be empty, a fresh orange, or a rotten orange, determine the minimum number of minutes until no fresh orange remains. Rotten oranges rot adjacent fresh oranges each minute. Return -1 if some fresh oranges can never rot.
From Amazon SDE1 AUTA Interview Experience — 1.5 YOE | 2024 Batch | July 26
- 17
Maximize Array Score by Reversing a Subarray
Given an array of integers, maximize the score of the array by reversing at most one contiguous subarray. The score of an array is defined as the sum of absolute differences between consecutive elements.
From Amazon | Applied Scientist Intern (6 Months) | Interview Experience
- 18
Minimum Moves in Grid with One Wall Break
Given a grid where 0 represents a wall and 1 represents free space, find the minimum number of moves to reach from the top-left corner (0,0) to the bottom-right corner (R-1, C-1). You can move in 4 directions and are allowed to break at most one wall.
From Amazon | Applied Scientist Intern (6 Months) | Interview Experience
- 19
Inventory Allocation with Bids and Round‑Robin
Given an integer totalInventory and a list of requests where each request is [customerId, quantity, bidAmount, timestamp], allocate items to customers based on: 1. Higher bidAmount has priority. 2. For equal bids, lower timestamp gets priority. 3. Within the…
From Inventory Allocation with Bids and Round-Robin Amazon OA
- 20
Text Editor / String Manipulation
Design and implement operations insert(string), print(x), left(x), right(x), backspace(x), delete(x) for a text editor supporting cursor movement and editing.
From Sharing Interview experience - Rubrik | Harness | Docusign
- 21
Array Optimization
Given an array of integers and an integer k, perform exactly k operations where each operation removes an element, divides it by 2 (ceiling), and adds it back. Return the minimum possible sum after k operations.
From Sharing Interview experience - Rubrik | Harness | Docusign
- 22
Count Substrings in a Binary String
Given a binary string, count substrings where all 0s and 1s are contiguous and the number of 0s equals the number of 1s.
From Sharing Interview experience - Rubrik | Harness | Docusign
- 23
String Encoding and Decoding
Design an encoding and decoding mechanism for strings.
From Sharing Interview experience - Rubrik | Harness | Docusign
- 24
Graph Optimization – Toll Price Increase
Given n cities connected by roads with toll prices, identify the road whose toll increase maximizes the average price increase across all routes from city 0 to city n‑1.
From Sharing Interview experience - Rubrik | Harness | Docusign
- 25
Count possible tokens per position in rooted directed tree
A collection contains N uniquely labeled tokens connected by one-way dependency links. The structure is guaranteed to form a rooted directed tree: exactly one token has no incoming link, and every other token has exactly one incoming link. Every link points…
53 more in the Interview Experience write-ups.
Interview Experience system design questions
- 01
Design Rule Engine for Driver Payouts
Design a rule engine that calculates driver payouts based on a set of rules stored in a database.
- 02
Payment Reconciliation System
Design a high‑level architecture for a system that reconciles payments across multiple financial platforms.
- 03
Movies Category Subscription Pricing
Design a low‑level solution for a subscription service where movies are grouped into categories and pricing varies by category.
- 04
Design Telemetry System
Create a high‑level design for a telemetry system that collects, aggregates, and visualizes streaming data from distributed sources.
- 05
Design Payment System
Design a low‑level architecture for a payment processing system handling transactions, refunds, and fraud detection.
- 06
Design Alert System for Payment Gateway Outages
Design a high‑level system that monitors payment gateway health and triggers alerts in case of outages.
- 07
Live Tracking Service Design
Design a high‑level architecture for a real‑time location tracking system.
From Sharing Interview experience - Rubrik | Harness | Docusign
- 08
Checkout Service for E‑commerce Platform
Design a distributed checkout system focusing on security, authentication, inventory failures, payment handling, refunds, and reliable transaction processing.
From Sharing Interview experience - Rubrik | Harness | Docusign
- 09
Synchronizing Two Large In‑Memory Hash Maps
Two nodes (USA and Europe) each hold a ~32 GB hash map of key→{data, version}. At most 5% of entries differ. Design a method to synchronize the maps minimizing data transfer, using version and source‑of‑truth rules.
From Sharing Interview experience - Rubrik | Harness | Docusign
- 10
Thread‑Safe Parking Lot System
Design a thread‑safe system for a one‑dimensional parking lot where cars occupy 1 spot and trucks occupy 2 consecutive spots, supporting concurrent parking and removal.
From Sharing Interview experience - Rubrik | Harness | Docusign
- 11
Asynchronous Task Processor Design
Design an asynchronous task processing system that supports scheduling tasks at a specific time, recurring intervals, and manages task execution.
From Sharing Interview experience - Rubrik | Harness | Docusign
- 12
Top‑N Movie Recommendation System
Design a system to recommend the top N movies based on views collected over the last 7 days, handling view tracking, time‑windowed aggregation, ranking, and scalability.
From Sharing Interview experience - Rubrik | Harness | Docusign
- 13
Design a YouTube‑like video storage system
Design a system that supports uploading, downloading, streaming, and searching videos. Functional requirements include handling video chunking, storage, post‑processing, manifest generation, search indexing, CDN delivery, and scaling for large traffic. Key…
- 14
Design Access Control Layer for SaaS Tool
Design an access control layer for a SaaS application covering Role‑Based Access Control (RBAC), Attribute‑Based Access Control (ABAC), and Relationship‑Based Access Control (ReBAC). Include data modelling for permissions in the database and discuss how the…
From Prep and Interview Exp for Senior/Staff level. Walmart, Amazon, Licious and few other startups
- 15
Live Collaboration Tool like Google Docs
Design a real‑time collaborative document editing service similar to Google Docs. Discuss the algorithms for concurrent editing (Operational Transformation or CRDT), the system components, data storage, and how you would scale to many concurrent users.
From Prep and Interview Exp for Senior/Staff level. Walmart, Amazon, Licious and few other startups
- 16
Design LFU Cache with TTL
Design a Least Frequently Used (LFU) cache that also supports a Time‑To‑Live (TTL) for each entry. The cache should evict items based on usage frequency while respecting expiration times.
From Prep and Interview Exp for Senior/Staff level. Walmart, Amazon, Licious and few other startups
- 17
Distributed Rate Limiter
Design a distributed rate‑limiting service for an internal API. Each upstream service has a fixed throughput limit per API key. Requests that exceed the limit should be queued, not rejected, and spare capacity from one service should be usable by another. The…
From Prep and Interview Exp for Senior/Staff level. Walmart, Amazon, Licious and few other startups
- 18
Design Search Bar for AWS Console UI
Design the backend for a search bar in the AWS console that lets users search for services. Results should be ranked by recency of use. The design must consider provisioning, deployment, and scaling within Amazon's control plane.
From Prep and Interview Exp for Senior/Staff level. Walmart, Amazon, Licious and few other startups
- 19
Design Hospital Management System (LLD)
Create a class diagram and a minimal implementation for a hospital management system covering patients, doctors, appointments, and billing.
From Prep and Interview Exp for Senior/Staff level. Walmart, Amazon, Licious and few other startups
- 20
Cash Register OOP Design
Design an object‑oriented cash register system that processes transactions and prints a receipt. The design should cover classes, responsibilities, and interactions needed to handle typical purchase flows.
- 21
Handle 10x UPI Transaction Spike During Flash Sale
"10x UPI transaction spike during flash sale. bank PSP can't be scaled. How would you design the system to handle this situation?"
From fintech system design interviews are different. heres what phonepe, razorpay, stripe actually ask.
- 22
Diagnose Drop in Payment Success Rate After Deploy
"Payment success rate dropped 3% after deploy, no alerts firing. Identify the root cause and propose a solution."
From fintech system design interviews are different. heres what phonepe, razorpay, stripe actually ask.
- 23
Prevent Double Debit on Client Retry After Backend Success
"User's payment times out but succeeded on backend. They retry. How do you prevent double debit?"
From fintech system design interviews are different. heres what phonepe, razorpay, stripe actually ask.
- 24
Design Ledger Service with Instant UI Updates and Strong Consistency
"Design the ledger service. Product wants instant UI updates. Infra wants consistency. How do you resolve this trade‑off?"
From fintech system design interviews are different. heres what phonepe, razorpay, stripe actually ask.
- 25
Handle Bank Rate‑Limit of 1000 TPS When Service Sends 5000 TPS
"Your service does 5000 TPS. Bank rate‑limits at 1000 TPS. What do you do?"
From fintech system design interviews are different. heres what phonepe, razorpay, stripe actually ask.
6 more in the Interview Experience write-ups.
Interview Experience other questions
- 01
Residual Connections in Neural Architecture
What are residual connections, and why did you use them in your architecture?
From Amazon | Applied Scientist Intern (6 Months) | Interview Experience
- 02
Vanishing Gradient Problem and Solutions
What is the vanishing gradient problem? What are the common solutions to mitigate it?
From Amazon | Applied Scientist Intern (6 Months) | Interview Experience
- 03
Avoiding Sigmoid Activation in Hidden Layers
Why do we avoid using the Sigmoid activation function in the hidden layers of neural networks? Compare different activation functions (Sigmoid, Tanh, ReLU, Leaky ReLU) along with their pros and cons. In Leaky ReLU, why do we keep small alpha value? What…
From Amazon | Applied Scientist Intern (6 Months) | Interview Experience
- 04
Channel Growth in DenseNet Dense Blocks
What happens to the number of channels across dense blocks in DenseNet?
From Amazon | Applied Scientist Intern (6 Months) | Interview Experience
- 05
Computing Output Dimensions After Convolution
How do you compute the output dimension when applying a specific filter size to an image of given dimensions?
From Amazon | Applied Scientist Intern (6 Months) | Interview Experience
- 06
Effectiveness of 1x1 Convolutions
Can small filters (1 x 1 convolutions) learn meaningful features in an image?
From Amazon | Applied Scientist Intern (6 Months) | Interview Experience
- 07
Loss Functions and Categorical Cross-Entropy
What are different types of loss functions, and when/why are they used? Explain Categorical Cross-Entropy (CCE). How does it mathematically penalize wrong predictions severely?
From Amazon | Applied Scientist Intern (6 Months) | Interview Experience
- 08
Transformer Architectures and Attention Details
What are the different Transformer architectures you know (Encoder-only, Decoder-only, Encoder-Decoder)? How does the attention mechanism differ across these architectures? In masked attention, what is the preferred sequence of operations: applying masking…
From Amazon | Applied Scientist Intern (6 Months) | Interview Experience
- 09
Kernels in Support Vector Machines
What is the concept of kernels in Support Vector Machines (SVM)? What are the different types of kernels, and when would you use each?
From Amazon | Applied Scientist Intern (6 Months) | Interview Experience
- 10
Test the Hypothesis
Given two numeric datasets and a confidence level, perform a two‑tailed t‑test to decide whether the means are significantly different. Return "Yes" if they are, otherwise "No", along with the magnitude |tcomputed ‑ tcritical| rounded to two decimals.…
- 11
Interview Experience interview questions FAQ
What questions are asked in Interview Experience interviews?
Candidates reported 120 distinct questions across 35 Interview Experience interviews. 78 coding and DSA questions, 31 system design questions, 11 other questions.
Which Interview Experience interview questions are asked most often?
The most repeated are "Kth Smallest Element in a BST" (2 times).
How difficult are Interview Experience interview questions?
Of the questions candidates rated, 0% were easy, 71% medium and 29% hard.