START
  │
  ├─ Unweighted graph + shortest path?
  │     └──→ BFS
  │
  ├─ Weighted graph + shortest path (no negative)?
  │     └──→ Dijkstra
  │
  ├─ Weighted graph + negative edges?
  │     └──→ Bellman-Ford
  │
  ├─ All-pairs shortest path?
  │     └──→ Floyd-Warshall
  │
  ├─ Cycle detection?
  │     ├─ Undirected → DFS with parent tracking
  │     └─ Directed  → DFS with recursion stack (or Kahn's)
  │
  ├─ Connected components / island counting?
  │     └──→ DFS or BFS or Union-Find
  │
  ├─ Task ordering / prerequisites?
  │     └──→ Topological Sort (Kahn's or DFS)
  │
  ├─ Minimum spanning tree?
  │     ├─ Sparse graph → Kruskal's
  │     └─ Dense graph  → Prim's
  │
  ├─ Dynamic connectivity / union queries?
  │     └──→ Union-Find
  │
  └─ Multiple sources, equidistant spread?
        └──→ Multi-source BFS

// Default: Build adjacency list
const graph = new Map();
for (const [u, v] of edges) {
  if (!graph.has(u)) graph.set(u, []);
  if (!graph.has(v)) graph.set(v, []);
  graph.get(u).push(v);
  graph.get(v).push(u); // For undirected
}