using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    public static void Main()

    {

        var trackHard = new DifficultyTrack(TrackDifficulty.Hard, new Dictionary<NormalizedDifficulty, int>

        {

            [NormalizedDifficulty.VeryEasy] = 0,

            [NormalizedDifficulty.Easy] = 10,

            [NormalizedDifficulty.Medium] = 55,

            [NormalizedDifficulty.Hard] = 35

        });

        var trackMedium = new DifficultyTrack(TrackDifficulty.Medium, new Dictionary<NormalizedDifficulty, int>

        {

            [NormalizedDifficulty.VeryEasy] = 0,

            [NormalizedDifficulty.Easy] = 20,

            [NormalizedDifficulty.Medium] = 70,

            [NormalizedDifficulty.Hard] = 10

        });

        var trackEasy = new DifficultyTrack(TrackDifficulty.Easy, new Dictionary<NormalizedDifficulty, int>

        {

            [NormalizedDifficulty.VeryEasy] = 0,

            [NormalizedDifficulty.Easy] = 35,

            [NormalizedDifficulty.Medium] = 65,

            [NormalizedDifficulty.Hard] = 0

        });

        var trackVeryEasy = new DifficultyTrack(TrackDifficulty.VeryEasy, new Dictionary<NormalizedDifficulty, int>

        {

            [NormalizedDifficulty.VeryEasy] = 40,

            [NormalizedDifficulty.Easy] = 40,

            [NormalizedDifficulty.Medium] = 20,

            [NormalizedDifficulty.Hard] = 0

        });

        var tracks = new [] {trackHard, trackMedium, trackEasy, trackVeryEasy};

        var p1 = new DifficultyBreakdown

        {

            VeryEasy = 40,

            Easy = 41,

            Medium = 20,

            Hard = 0

        };

        var nearestTrack = tracks.OrderBy(t => t.CalculateDistance(p1)).First();

        var distance = nearestTrack.CalculateDistance(p1);

        Console.WriteLine($"{nearestTrack.Difficulty} - {distance:p2}");

    }

}

​

public enum TrackDifficulty

    {

        Unknown = 0,

        VeryEasy = 1,

        Easy = 2,

        Medium = 3,

        Hard = 4

    }

public enum NormalizedDifficulty

    {

        Unknown = 0,

        VeryEasy = 1,

        Easy = 2,

        Medium = 3,

        Hard = 4

    }

public class DifficultyBreakdown

    {

        public double VeryEasy { get; set; }

        public double Easy { get; set; }

        public double Medium { get; set; }

        public double Hard { get; set; }

    }

​

public class DifficultyTrack

    {

        public DifficultyTrack(TrackDifficulty trackDifficulty, Dictionary<NormalizedDifficulty, int> targets)

        {

            Difficulty = trackDifficulty;

​

            Targets = new Dictionary<NormalizedDifficulty, double>();

            foreach (var kvp in targets)

            {

                Targets.Add(kvp.Key, kvp.Value / 100d);

            }

        }

​

        public TrackDifficulty Difficulty { get; }

        public Dictionary<NormalizedDifficulty, double> Targets { get; }

​

        public double CalculateDistance(DifficultyBreakdown difficultyBreakdown)

        {

            var res = 0d;

​

            res += Math.Abs(Targets[NormalizedDifficulty.VeryEasy] - difficultyBreakdown.VeryEasy);

            res += Math.Abs(Targets[NormalizedDifficulty.Easy] - difficultyBreakdown.Easy);

            res += Math.Abs(Targets[NormalizedDifficulty.Medium] - difficultyBreakdown.Medium);

            res += Math.Abs(Targets[NormalizedDifficulty.Hard] - difficultyBreakdown.Hard);

​

            return res;

        }

    }