juniorGraph Theory
Self-loops and Multiple Edges?
Updated Apr 28, 2026
Short answer
A self-loop connects a vertex to itself; multiple edges connect the same two vertices.
Deep explanation
Graphs are versatile structures for representing networks. A self-loop connects a vertex to itself; multiple edges connect the same two vertices. 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?