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CSharp · Console

/Program.cs

using System;
using System.Collections.Generic;
using System.Linq;
					
    class Program
    {
        public static List<Human> humans = new List<Human>()
        {
            new Human
            {
                FirstName="Karl",
                LastName="Karlson",
                clothings=new List<Clothing>()
                {
                    new Clothing
                    {
                        Garment="T-Shirt",
                        Color="pink"
                    },
                    new Clothing
                    {
                        Garment="Pant",
                        Color="white"
                    },
                    new Clothing
                    {
                        Garment="Shoes",
                        Color="black"
                    }
                }
            },
            new Human
            {
                FirstName="Paula",
                LastName="Paulson",
                clothings=new List<Clothing>()
                {
                    new Clothing
                    {
                        Garment="T-Shirt",
                        Color="red"
                    },
                    new Clothing
                    {
                        Garment="Pant",
                        Color="blue"
                    },
                    new Clothing
                    {
                        Garment="Shoes",
                        Color="black"
                    },
					new Clothing
					{
						Garment = "RandomGarment", //<- added a new clothing
						Color = "RandomColor"
					}
                }
            }
        };

        public static List<CurrentClothes> currentclothes = new List<CurrentClothes>()
        {
            new CurrentClothes
            {
                Garment = "Pant",
                Color = "blue"
            },
            new CurrentClothes
            {
                Garment = "T-Shirt",
                Color = "red"
            },
            new CurrentClothes
            {
                Garment = "Shoes",
                Color = "black"
            }
        };

        static void Main(string[] args)
        {
            var currentclothesAsHashSet = currentclothes.ToHashSet();
            var human = humans.Where(x => !currentclothesAsHashSet.Except(x.clothings.OfType<CurrentClothes>().ToHashSet()).Any());
            foreach (var human1 in human)
            {
                Console.WriteLine(human1.FirstName);
            }
        }
    }

    public class Human
    {
        public string FirstName { get; set; }
        public string LastName { get; set; }
        public List<Clothing> clothings { get; set; }
    }

    public class Clothing : CurrentClothes
    {
        public string ClothingID { get; set; }
    }

    public class CurrentClothes : IEquatable<CurrentClothes>
    {
        public string Garment { get; set; }
        public string Color { get; set; }

        public override bool Equals(object obj) => ReferenceEquals(this, obj) || obj is CurrentClothes other && Equals(other);
        public bool Equals(CurrentClothes other)
        {
            if (ReferenceEquals(null, other)) return false;
            if (ReferenceEquals(this, other)) return true;
            return Garment == other.Garment && Color == other.Color;
        }
        public override int GetHashCode() => HashCode.Combine(Garment, Color);
    }