Line Graph — DSA Technical Interview Questions & Answers

Line Graph

Line Graph

  • Line Graph is a DSA topic. In plain words you use it for bus routes in a city map. Don’t start with a slogan — start with that picture.
  • Smallest example: BFS queue / DFS stack. Type it, run it, and say what you see. If you can do that from memory, you know Line Graph.
  • From the example next to this theory: Line Graph — graphs are often stored as adjacency lists: vertex → list of (neighbor, weight).
  • Trap: no visited set → infinite loop. Fix that before you talk about advanced DSA.
  • Viva: what is Line Graph? Then show BFS queue / DFS stack. Then name the trap.

Technical Interview Tip: What is Line Graph? Show this: BFS queue / DFS stack. Trap: no visited set → infinite loop.

Code Examples for Line Graph

Line Graph — working example

# adjacency list
graph = {
    "A": [("B", 2), ("C", 5)],
    "B": [("A", 2), ("C", 1)],
    "C": [("A", 5), ("B", 1)],
}
for u, edges in graph.items():
    print(u, "->", edges)

Line Graph — graphs are often stored as adjacency lists: vertex → list of (neighbor, weight).

How to Explain Line Graph to an Interviewer

What is Line Graph?

Used for bus routes a city map Not just the heading

Give one small example of Line Graph.

BFS queue / DFS stack Line Graph — graphs are often stored as adjacency lists: vertex → list of (neighbor, weight)

What mistake do beginners make with Line Graph?

no visited set → infinite loop Show the fix

Where do you use Line Graph?

a city map bus routes