DSA · Theory

Graph Representation

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Theory

37/810

Graph Representation

If you can teach Graph Representation using bus routes, you know it. If you only know the heading, you don’t.

Keep Graph Representation small. Sara should finish bus routes in a few lines, not a 40-line dump.

Skip Graph Representation and no visited set → infinite loop shows up in a city map.

Use Graph Representation when bus routes must stay clear. If a simpler DSA step works, use that instead.

If bus routes breaks under Graph Representation, check no visited set → infinite loop first.

After Graph Representation, Sara should still remember no visited set → infinite loop.

One breath for Graph Representation, then bus routes, then no visited set → infinite loop. Sit down.

Exam tip

For Graph Representation: definition + a city map + one failure.

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)

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

Short notes

DefGraph Representation — Sara uses it for bus routes in a city map.
RuleGraph Representation → BFS queue / DFS stack.
RememberGraph Representation + time vs memory (a city map).
UseGraph Representation in a city map (bus routes).
TrapGraph Representation — no visited set → infinite loop.
ExGraph Representation → bus routes.

DSA · Theory

Graph Representation

← All stacks

Theory

37/810

Graph Representation

If you can teach Graph Representation using bus routes, you know it. If you only know the heading, you don’t.

Keep Graph Representation small. Sara should finish bus routes in a few lines, not a 40-line dump.

Skip Graph Representation and no visited set → infinite loop shows up in a city map.

Use Graph Representation when bus routes must stay clear. If a simpler DSA step works, use that instead.

If bus routes breaks under Graph Representation, check no visited set → infinite loop first.

After Graph Representation, Sara should still remember no visited set → infinite loop.

One breath for Graph Representation, then bus routes, then no visited set → infinite loop. Sit down.

Exam tip

For Graph Representation: definition + a city map + one failure.

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)

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

Short notes

DefGraph Representation — Sara uses it for bus routes in a city map.
RuleGraph Representation → BFS queue / DFS stack.
RememberGraph Representation + time vs memory (a city map).
UseGraph Representation in a city map (bus routes).
TrapGraph Representation — no visited set → infinite loop.
ExGraph Representation → bus routes.

Graph Representation

Example

Short notes

Questions

Graph Representation

Example

Short notes

Questions