Pattern 14: Graph traversal (BFS/DFS on graphs and grids)
Comes up in: DSA
This concept is being written. It gets the full five steps — explanation, predict, interview angle, practice with tests, and review cards. Here is exactly what it will cover, so you can study it elsewhere in the meantime.
What it covers
- visited sets
- grid neighbours
- multi-source BFS
- BFS for shortest path in unweighted graphs
- connected components
Words you will know
What you will practise
- flood-fill (E)
- number-of-islands (M)
- clone-graph (M)
- rotting-oranges (M)
- pacific-atlantic (M)
- word-ladder (H)
Interview questions this answers
- Count the islands in a grid. What is the complexity?
- How do you detect a cycle in a directed graph?
- Why does BFS give the shortest path in an unweighted graph?