juniorGraph Theory
Directed vs. Undirected Graphs?
Updated Apr 28, 2026
Short answer
Directed graphs have edges with direction (arrows); Undirected edges are bidirectional.
Deep explanation
Graphs are versatile structures for representing networks. Directed graphs have edges with direction (arrows); Undirected edges are bidirectional. Adjacency matrices are O(1) for edge lookups but O(V^2) space, while lists are more space-efficient for sparse graphs.
Real-world example
Social media networks (friends/followers).
Common mistakes
- Using an Adjacency Matrix for a very sparse graph with millions of nodes.
Follow-up questions
- Space complexity of Adjacency List?