How do I approach Coding & Algorithms interview questions?

Coding & Algorithms questions require understanding of core concepts and practice. PracHub provides solutions with explanations to help you master coding & algorithms interviews.

What difficulty level is this interview question?

This is a Medium difficulty Coding & Algorithms question, commonly asked during Onsite rounds at Meta.

What role is this question designed for?

This question is commonly asked for Data Engineer candidates at Meta during technical interviews.

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Last updated: Mar 29, 2026

Quick Overview

The question evaluates competency in graph traversal, set operations, and adjacency-list manipulation for social-network style data. Commonly asked in Coding & Algorithms interviews for Data Engineer roles, it gauges the ability to reason about relationship aggregation, duplicate elimination, and algorithmic efficiency when computing friends-of-friends, representing a practical application of algorithmic and data-structure knowledge rather than a purely conceptual exercise.

Question

Given a dictionary such as {A:[B,C], B:[C,D], C:[E]}, return for a user U all people followed by U’s followees but not already followed by U. Order is irrelevant and duplicates must be removed.

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