Sort as Preprocessing

Find Duplicates In a sorted array, duplicates are always adjacent. One pass finds them all. Merge Intervals A classic problem: merge overlapping intervals. Sorting by start time makes overlaps easy to detect. K Closest Points The algorithms covered in this lesson all follow the same principle: choose a data structure or preprocessing step that reduces the number of comparisons you need to make at each stage. Advanced problem-solving strategies prepare you for the kind of complex, multi-step challenges found in real-world software development. Put your skills to the test with hands-on challenges in the Python Builder.

About This Interactive Section

This section is part of the Problem Solving: Advanced lesson on DataDriven, a free data engineering interview prep platform. Each section includes explanations, worked examples, and hands-on code challenges that execute in real time. SQL queries run against a live PostgreSQL database. Python runs in a sandboxed Docker container. Data modeling problems validate against interactive schema canvases. All content is framed around what data engineering interviewers actually test at companies like Meta, Google, Amazon, Netflix, Stripe, and Databricks.

How DataDriven Lessons Work

DataDriven combines four interview rounds (SQL, Python, Data Modeling, Pipeline Architecture) with adaptive difficulty and spaced repetition. Easy problems get harder as you improve. Weak concepts resurface until you master them. Your readiness score tracks progress across every topic interviewers test. Every lesson section ends with problems you solve by writing and running real code, not by picking multiple-choice answers.