Data Engineer Coding & Algorithms Interview Questions
Practice the exact questions companies are asking right now.
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Compute transaction fees from a CSV string
You are given a CSV string representing a list of payment transactions. Write a function that parses the CSV and returns a CSV string with the total p...
Write queries for follows and bookings
You are given tables/logs from a consumer app. Solve the following independent tasks. Part A — Active following as of a date (SQL) You have a follow e...
Write SQL using joins and window functions
SQL Coding: Rank within Groups with Joins You are given two tables: accounts - account_id (string) - customer_id (string) - segment (string) — e.g., "...
Solve SQL and Python coding tasks
You are given a small library system with the following relational schema and several Python data-processing tasks. Answer the SQL questions and imple...
Write SQL for session analytics
You are given two tables for an e-commerce product. Tables 1) shops A shop dimension table that contains duplicate rows for the same shop_id. Columns:...
Solve Two String Problems
You are asked to solve the following two coding problems: 1. Unique Morse Code Transformations You are given an array of lowercase English words, word...
Write SQL for car rental utilization by city
SQL / Data Query Prompt (Car Rental) You are given four tables: user - user_id location - location_id - city car - car_id - car_size (e.g., compact, m...
Aggregate user logs into 30-minute sessions
You are given a CSV file with columns: user_id | log_datetime | topic Example input rows (already in time order for the same user): - 001 | 2025-03-01...
Validate an IPv4 address string
Given a string s, determine whether it is a valid IPv4 address. A valid IPv4 address: - Has exactly 4 parts separated by dots (.): x1.x2.x3.x4 - Each ...
Write SQL for app metrics
You are given a simplified schema for a photo-sharing app: - users(user_id, user_name, joined_at) - photos(photo_id, user_id, created_at) - follows(fo...
Write SQL for first share and closest collaborator
You are given event data about users viewing design files. Assume the following tables: - files(file_id, creator_id) - creator_id is a VARCHAR user ...
Implement most_frequent_key without using max()
Problem (Python OOP) You are given two classes. Parent precomputes frequency counts of items (as strings) from an input list. `python class Parent: ...
Compute Max Score From Up to 3 Categories
You are implementing a scoring function for a library summer reading program. Each book a student read is represented as a tuple (category: str, point...
Compute capacities after site closures
You are given a nested dictionary redistribution where redistribution[closed_site][dest_site] equals the additional capacity required at dest_site if ...
Implement a stack supporting max and popMax
Design a data structure that behaves like a stack but also supports retrieving and removing the current maximum value. Implement a class MaxStack with...
Solve library coding tasks in Python
Implement the following Python tasks: 1) Given a list of (category, points) for books, choose up to 3 books with all different categories to maximize ...
Solve four algorithmic library problems
Solve the following coding tasks: 1) Maximum Points from Different Categories: Given an array of items (category, points) and an integer k, choose exa...
Count islands using BFS without modifying grid
You are given an m x n binary grid grid where: - 1 represents land - 0 represents water - Islands are groups of horizontally or vertically adjacent la...
Check carpool trip feasibility
You are given a list of trips where each trip i is (passengers_i, start_i, end_i) with start_i < end_i on a one-dimensional route. A single vehicle wi...
Implement classes within an abstract Python framework
You are given an existing Python codebase (~200 lines shown) that defines an abstract base class DataProcessor with abstract methods load(self), trans...