Capital One Interview Questions
Practice the exact questions companies are asking right now.
Solve OA tasks on string, grid path, subarrays
You are given three independent coding tasks. Task 1: Reverse the middle if ends are vowels Given a string s (ASCII letters), if both the first and la...
Design a highly reliable account balance system
Scenario You are designing a backend service that stores and updates user account balances (like a wallet/bank ledger). The system must be highly reli...
Design a cross-region event processing platform
Scenario Design a cross-region event processing platform that ingests events from producers, stores them durably, and delivers them to multiple consum...
Implement deposit, withdraw, and transfer in a class
Problem Implement a class AccountService that supports basic money operations on accounts. Operations - deposit(accountId, amount) - withdraw(accountI...
Simulate round-robin package assignment to servers
You are simulating a round-robin dispatcher across m servers labeled 0..m-1. - Each server i has an initial remaining capacity cap[i] (a non-negative ...
Validate virtual credit card transactions from encoded IDs
You are designing logic for a virtual credit card product. Part 1: Product reasoning Explain key benefits and drawbacks of virtual credit cards for: -...
Design a transaction class for deposits/withdrawals
Design a Transaction/Account component that supports deposits and withdrawals. Assume you are building a backend library or service used by other part...
Answer motivation and teamwork questions
You are in a behavioral interview for an entry-level software role. Answer the following prompts: 1. Why did you choose to study Computer Science? 2. ...
Decide on vegan-burger R&D investment
Investment Decision: Vegan Burger R&D and Launch Business Case You are evaluating whether to invest now in R&D to develop and launch a plant-based (ve...
Count ordered fragment pairs forming a password
You are given: - A target string password. - A list of N string fragments fragments[0..N-1] (fragments may repeat). Count the number of ordered pairs ...
Design model deployment, monitoring, and low-latency inference
You have trained a fraud detection model and need to productionize it. Part A: Deployment - How would you deploy an ML model to production? - What art...
Support updates and count target-sum pairs
You are given two integer arrays: - A (fixed / primary) - B (modifiable / secondary) You must process a sequence of operations of two types: 1. Update...
Compute minutes since last train departure
You are given a daily train timetable as a list of departure times (24-hour format HH:MM). Given the current time (also HH:MM), find the most recent d...
Compute credit-card portfolio profit and breakeven
A bank is evaluating a new credit card. Segments: A: 30,000 customers, capture rate 20%, avg annual spend per captured customer = $100,000. B: any pop...
Return all root-to-leaf tree paths
Given the root of a binary tree, return all root-to-leaf paths. - A leaf is a node with no children. - A path should be represented as a string with n...
Implement string/matrix simulations and counting pairs
You are given several independent implementation-focused tasks. For each task, write a function that returns the required value. Task 1 — Count matchi...
Design a robust fraud detection system
Real-Time Card Fraud Detector — End-to-End Design Context - Fraud base rate ≈ 0.2% (severe class imbalance) - Labels arrive with a 14-day delay (e.g.,...
Optimize invites under capacity constraints
You have n donors (n up to 100,000). For each donor i you know: p_online[i] (probability of donating if emailed), a_online[i] (expected donation condi...
Describe leadership challenges and managing a difficult report
Answer the following behavioral questions with specific examples: 1. In a project you led, what was the most challenging part and why? 2. Tell me abou...
Design a scalable banking system
System Design: Online Banking Platform Context Design an online banking platform (scope similar to a credit-card application system) that supports: - ...