Data Structures Series #4: Graphs - Implementation & Use Cases

Introduction Welcome back to the Data Structures series! So far we've covered Stacks, Queues, and Binary Trees. Today we're exploring one of the most versatile and powerful data structures in computer science: Graphs . From social networks to GPS navigation, graphs model relationships between things in ways other structures simply can't. Let's dig in. What is a Graph? A Graph is a non-linear data structure made up of vertices (also called nodes) and edges (connections between nodes). Unlike trees, graphs have no strict parent-child hierarchy — any node can connect to any other node. Key Terminology Vertex (Node): A single entity in the graph (e.g., a user, a city). Edge: A connection between two vertices. Directed Graph: Edges have a direction (A → B, but not B → A). Think Twitter followers. Undirected Graph: Edges go both ways (A — B). Think Facebook friends. Weighted Graph: Edges carry a cost or distance value. Think Google Maps routes. Adjacency: Two vertices are adjacent if they sh