Capital One Interview Questions — Page 4

Capital One·Product Manager·Onsite - System Design / Architecture

Apr 2026

Capital One PM interview with a system design flavored question about push notifications. Pretty technical for a product role, which I wasn't fully expecting.

What are the key technical elements and considerations you'd need to think through when building a push notification system for an app?

“I fumbled the opening a bit because I went straight to user-facing stuff like notification copy and timing, and the interviewer kind of steered me back toward the infrastructure side.”

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Capital One·Software Engineer·Onsite - Behavioral / Leadership

Apr 2026

Behavioral round at Capital One for a software engineering role. Two questions, both leadership-flavored, and the kind where they really want a specific story not a general answer.

In a project you led, what was the most challenging part and why?
Tell me about a time you worked with someone who resisted direction or pushed back on management. How did you handle it, and what happened?

“They wanted context upfront: team size, your actual role, not just a vague 'it was hard.' I talked through a backend migration I led with three other engineers and focused on the part where we had to cut scope mid-sprint to hit a deadline.”

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Capital One·Software Engineer·Online Assessment (OA)

Apr 2026

Capital One software engineer assessment with four coding problems ranging from array pair counting to a segment tree style placement query. The problems were independent and algorithmic, no behavioral stuff from what I could tell. Mix of easy and genuinely hard.

Given an integer array, count the number of index pairs (i, j) where i < j and the values at both indices are equal. Expected O(n) time and O(n) space.
Simulate a match-three style board game: repeatedly find all horizontal or vertical runs of 3+ identical letters, remove them, apply gravity so letters fall down, and repeat until no more removals. Return the final board state.
Given an n x n matrix, check whether every cell on the main diagonal and anti-diagonal is nonzero, and every cell NOT on either diagonal is zero.
Design a data structure for N positions (1 to N). Support two operations: mark a range [l, r] as occupied, and find the leftmost start of a contiguous unoccupied segment of length k. Both N and the number of queries can be up to 2x10^5, so aim for near O((N+Q) log N) total time.

“Classic frequency map problem.”

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Capital One·Software Engineer·Online Assessment (OA)

Apr 2026

Capital One OA with 4 coding problems. First two were manageable, last two were brutal and I barely scraped by on test cases. None of the questions showed up on Leetcode, which tells you something.

Coding problem 1 (easy-medium difficulty): a straightforward algorithmic problem where full marks were achievable with a clean solution.
Coding problem 2 (medium-hard difficulty): a more complex algorithmic problem requiring careful handling of edge cases.
Coding problem 3 (hard difficulty): a highly nuanced problem involving segmented array queries, similar to tracking segments after removal operations on an array of elements.
Coding problem 4 (hard difficulty): another highly nuanced algorithmic problem with obscure edge cases, not found on any standard practice platform.

“Got all test cases on this one, 300/300.”

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Capital One·Software Engineer·Technical Phone Screen

Apr 2026

Capital One software engineer screen with a single coding problem. Pretty straightforward premise but the edge cases are where it gets you.

Given an array of integers and a target value, count how many elements are strictly greater than the target and how many are strictly less. Return 'greater', 'smaller', or 'tie' based on which count is higher. Elements equal to the target don't count toward either side.

“Seemed easy at first and I jumped straight into iterating the array, which was fine.”

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Capital One·Data Scientist·Technical Phone Screen

Apr 2026

Capital One data scientist interview with a straightforward profitability math question for a loyalty program. Nothing too wild conceptually, but the arithmetic has enough moving parts that you can trip yourself up if you're not careful with units.

A loyalty program has 2 million customers. Annual fee is $50 per customer, plus a 1% commission on monthly spending of $500 per customer. Fixed annual costs are $250 million, variable costs are $5 per customer per year. Calculate total annual revenue, total annual cost, total annual profit, and profit per customer.

“The commission piece is where I slowed down.”

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Capital One·Software Engineer·Technical Phone Screen

Apr 2026

Capital One SWE interview with a text justification coding problem. Pretty standard algorithmic question but the edge cases will get you if you're not careful.

Implement a function that takes a list of words and a maximum line width, and returns the words justified to fit within that width.

“I jumped straight into the greedy packing logic and felt good about it, then completely fumbled the spacing distribution.”

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Capital One·Software Engineer·Technical Phone Screen

Apr 2026

Capital One SWE interview with a matrix manipulation problem. Nothing too wild conceptually but the rotate command tripped me up more than I expected.

Given an integer matrix and a list of string commands, implement each command (reverseRow, swap rows, or 90-degree clockwise rotation) and return the final matrix state.

“The reverseRow and swap parts were fine, pretty mechanical.”

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Capital One·Data Scientist·Technical Phone Screen

Apr 2026

Capital One data scientist round, basically one big SQL problem that took the whole session. The question was about reconstructing lost revenue from a database outage and it was way more involved than I expected going in.

A database outage prevented premium membership registrations from being recorded for a three-month window. Given tables for intended enrollments, actual registrations, and the outage dates, write a single PostgreSQL query that returns total revenue lost and a breakdown by how many months each user missed, using calendar month boundaries and handling NULLs for users who never registered.

“This wrecked me a little.”

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Capital One·Data Scientist·Technical Phone Screen

Apr 2026

Capital One DS interview that was basically one giant ML case study on airline delay prediction. The question had like seven sub-parts and covered everything from feature engineering to productionization. A lot to hold in your head at once.

Given flight delay data with columns like departure/arrival times, carrier, weather features, and a holiday flag, how would you define a binary target variable and justify your choice?
How would you construct a leakage-aware feature set for predicting flight delays, given that some columns encode future information?
Describe how you would set up a time-based train/validation/test split, handle class imbalance, and choose evaluation metrics for this problem.
Compare a regularized logistic regression baseline with target encoding against a gradient boosting model. What hyperparameters would you tune and would you use any monotonic constraints?
How would you implement rolling-origin cross-validation and backtest operational threshold policies using cost-sensitive evaluation where false negatives are penalized five times more than false positives?
How would you productionize this model under constraints of 20ms latency per flight, a 50MB model size limit, and requirements for drift detection and retraining cadence?
What deliverables would you produce for this project, including documentation, fairness analysis, and an executive summary with ROI estimates?

“I went with arr_delay_min > 15 because that's actually the FAA definition of a late arrival, so you're not just making up a threshold.”

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