Display the First Three Rows

Display the First Three Rows

What is this problem about?

The Display the First Three Rows interview question is a foundational task in data manipulation, typically asked in the context of Pandas (Python) or SQL. Given a dataset (like a DataFrame or a table), you need to retrieve and display only the first three rows. This is essentially the equivalent of the head(3) method in Pandas or the LIMIT 3 clause in SQL.

Why is this asked in interviews?

Meta, Amazon, and Google use this simple question to verify basic literacy in data science tools and database management. It’s a "sanity check" to ensure a candidate understands how to inspect a dataset. In high-pressure environments, being able to quickly slice or limit data is crucial for debugging and exploratory data analysis. It tests whether you know the standard syntax for basic row filtering in your preferred language.

Algorithmic pattern used

This is a Slicing or Selection problem. In Python (Pandas), you use index-based slicing [:3] or the specialized .head() method. In SQL, you use the LIMIT or TOP keyword. From an algorithmic perspective, it’s an $O(1)$ operation (if the data is already in memory) or an $O(k)$ operation (where $k$ is the number of rows to retrieve) because you simply stop after the third element.

Example explanation