Why should you care?

Lists train null checks and in-place rewiring.

See it live — copy this example

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

public class ListNode {
  public int Val; public ListNode Next;
  public ListNode(int v, ListNode next = null) { Val = v; Next = next; }
}
// Fast and Slow Pointers

What happened?

• Draw nodes before coding.
• Always handle empty/single-node cases.

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 Fast and Slow Pointers. You know the complexity class. You tested at least one edge case.

Fast and Slow Pointers drill

AlgoVerse interview prompt on fast and slow pointers.

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