Graphs and Network Algorithms · Graphs

Adjacency List

An adjacency list stores each vertex with its neighbors, usually saving space when most vertices connect to only a few others.

Student Focus

This representation is used heavily in coding practice because it fits most student graph problems.

Guided Lesson Notes

How Code Scholars teaches Adjacency List

This guide helps students understand the idea, implement it carefully, explain the runtime, and recognize when the pattern belongs in a larger problem.

In a session, students usually start with a small trace, then write or review code, then test edge cases. The final step is a short explanation: what the structure or algorithm stores, why it is correct, and what changes when the input grows.

Key Ideas

  • Neighbor lists
  • Sparse graph efficiency
  • Iteration over outgoing edges

Practice Prompts

  • Build adjacency lists using arrays of lists or maps.
  • Trace how BFS reads neighbors from an adjacency list.

Tutoring Connection

Turn the topic into usable problem-solving skill

Students can use this page before a lesson, after a difficult homework assignment, or while preparing for AP Computer Science A extensions, Advanced Topics in CS, USACO growth, or a college data structures course.