Hs

CSharp · Console

/Program.cs

using System;
using System.Collections.Generic;
using System.Linq;
					
public class MyComparer : IEqualityComparer<List<int>> {
  public bool Equals(List<int> A, List<int> B) {
    if (ReferenceEquals(A, B))
      return true;
    if (A is null || B is null)
      return false;

    return A.SequenceEqual(B);
  }

  public int GetHashCode(List<int> list) => list is null
    ? -1
    : list.Count;
}

public class Program {
  public static void Main()	{
    var hs = new HashSet<List<int>>(new MyComparer());
	  
	List<int> list = new List<int>() { 1, 2, 3 };
    hs.Add(new List<int>(){1, 2, 3});
    hs.Add(list);
	  
	Console.WriteLine($"{hs.Count}");   
  }
}