Capital One Coding & Algorithms Interview Questions
Practice the exact questions companies are asking right now.
Solve string merge and grid path tasks
Question Given two equal-length strings s1 and s2, create a new string by iterating i = 0 … n-1, comparing s1[i] with s2[n-1-i]: append s1[i]; if the ...
Automate Python Virtual Environment Setup on Linux Terminal
Scenario Shell script that automates Python virtual-environment setup on a Linux terminal during a tech interview Question Walk through the script lin...
Explain Python Virtual Environment Setup and Function Analysis
Scenario Technical screen where candidate and interviewer jointly walk through Python code snippets used in a data-science repository. Question Show h...
Explain Shell Script Line-by-Line for Data Science Workflows
Scenario Technical screening for a Principal Data Scientist: reviewing shell script and Python classes Question Explain, line by line, what the provid...
Solve matrix rotation and 1-D illumination
Question LeetCode 48. Rotate Image – rotate an n×n matrix 90° clockwise (extra space allowed). Find the point(s) with the maximum number of illuminate...
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...
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...
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...
Design late-tolerant streaming window aggregator
You receive an unbounded stream of events: (event_time, user_id, category). Events may arrive up to 48 hours late and are not ordered by time. Design ...
Implement minimal-cost overtime/contractor allocation
You must cover H extra engineering hours this week at minimum cost using employee overtime and optional contractors. Each employee i has a maximum ove...
Debug and test a Python function in venv
Consider the Python snippet below. """ import math def accumulate(nums, start=0, cache={}): total = start for n in nums: if n % 2 == 0: nums.appen...
Fix failing tests and refactor code
You're given a small Python repo. After creating and activating a clean virtual environment, installing requirements, and running "pytest -q", two tes...
Refactor code and enforce robustness
Code Review and Refactor: Summing a CSV Column Context You are reviewing a short Python script that sums a numeric column from a CSV using pandas. You...
Maximize grid-path expression and count sawtooth subarrays
Problem 1: Maximize a valid expression along a grid path You are given an m x n grid grid. Each cell contains either: - an operator: '+' or '-', or - ...
Find lexicographically smallest string and elimination order
You remember two coding questions from an online assessment. Question 1: Return the lexicographically smallest string after a prefix/suffix reverse Yo...
Apply commands to transform a matrix
You are given an integer matrix A of size n × m and a list of string commands to apply in order. Implement the commands and return the final matrix. C...
Count ordered pairs that concatenate to target
Given a list of integers numbers and an integer target, count the number of ordered pairs (i, j) with i != j such that concatenating numbers[i] follow...
Rotate matrix and find max lamp coverage
1) Square-matrix rotation with extra space: Given an n x n integer matrix, return a new matrix that is the 90-degree clockwise rotation of the input. ...
Solve powers, phases, grid pops, and swaps
Solve the following four problems: 1) Count powers of k in an array: Given an array of positive integers nums and an integer k >= 1, return how many e...
Solve four algorithmic coding tasks
You will solve four independent coding tasks: 1) Count equal-value pairs in an array: Given an integer array nums of length n, return the number of in...