Why should you care?

Networks, grids, and dependencies become graph problems.

See it live — copy this example

Run snippets in a .NET console app, LINQPad, or https://dotnetfiddle.net. Write Big O above every solution.

var g = new Dictionary<int, List<int>>();
void AddEdge(int u, int v) {
  if (!g.ContainsKey(u)) g[u] = new();
  g[u].Add(v);
}
// Floyd-Warshall

What happened?

• Build adjacency first; then BFS/DFS/shortest path.
• Follow the steps below — typing the code yourself is the fastest way to learn.

Practice next

1. Type the snippet in a C# console or LINQPad.
2. Write Big O on top of your solution.
3. Test empty / single-element edge cases.
4. Add a failing test then fix it.
5. Rename variables to domain words.

Remember

You can code a small C# example for Floyd-Warshall. You know the complexity class. You tested at least one edge case.

Floyd-Warshall drill

AlgoVerse interview prompt on floyd-warshall.

Outcome: You recognize the pattern and ship a correct C# sketch.