Refactor: problem constructors should take graph as input, not raw vertices/edges

[GiggleLiu]

Motivation

Problem types like KColoring, MaximumIndependentSet, MaxCut, etc. currently have new(num_vertices, edges) constructors that internally construct a SimpleGraph. This makes the problem "pretend to be a graph" and hides the graph topology type from the constructor signature.

Current pattern

// Graph construction is hidden inside the problem
let problem = MaximumIndependentSet::<SimpleGraph, i32>::new(4, vec![(0, 1), (1, 2)]);

Proposed pattern

// Graph is an explicit input — topology type is clear
let graph = SimpleGraph::new(4, vec![(0, 1), (1, 2)]);
let problem = MaximumIndependentSet::new(graph, weights);

Benefits:

• Graph topology type is reflected in the constructor signature
• Problems don't duplicate graph construction logic
• from_graph becomes new, which is more idiomatic
• Works naturally with non-SimpleGraph topologies (UnitDiskGraph, GridGraph, etc.)

Affected types (9 total)

All in src/models/graph/:

Type	Current constructor
MaximumIndependentSet	new(num_vertices, edges)
MinimumVertexCover	new(num_vertices, edges)
MinimumDominatingSet	new(num_vertices, edges)
MaximumClique	new(num_vertices, edges)
MaximalIS	new(num_vertices, edges)
KColoring	new(num_vertices, edges)
MaxCut	new(num_vertices, edges_with_weights)
MaximumMatching	new(num_vertices, edges_with_weights)
TravelingSalesman	new(num_vertices, edges_with_weights)

Each already has a from_graph(graph, ...) constructor that takes the graph directly. The refactoring would:

1. Remove new(num_vertices, edges)
2. Rename from_graph → new
3. Update all call sites (tests, examples, reductions)