Two-Pointer Technique

The two-pointer technique uses two indices that move through an array in a coordinated way. It's powerful for problems involving pairs, palindromes, or partitioning. Opposite Ends Pattern Start one pointer at the beginning and one at the end. Move them toward each other based on some condition. Two Sum with Sorted Array Same Direction Pattern Both pointers start at the beginning. A "fast" pointer explores while a "slow" pointer marks a position. This pattern applies whenever sorted data lets you make a decision that rules out one side. Palindrome checking, three-sum problems, and container-with-most-water all follow the same logic.

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.

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