using System;

​

//A cloud, a cloud can be classified based on it's type.

//There are 10 different cloud types.

public class Cloud : IComparable<Cloud>, IEquatable<Cloud>

{

    public CloudType Type

    {

        get;

        set;

    }

​

    public Cloud(CloudType type)

    {

        Type = type;

    }

​

    public int CompareTo(Cloud obj)

    {

        if ((int)this.Type == (int)obj.Type)

            return 0;

        if ((int)this.Type < (int)obj.Type)

            return -1;

        if ((int)this.Type > (int)obj.Type)

            return 1;

        return 1;

    }

​

    public enum CloudType

    {

        Level10,

        Level20,

        Level30,

        Level40,

        Level50,

        Level60,

        Level70,

        Level80,

        Level90,

        Level100

    }

​

    public bool Equals(Cloud other)

    {

        if (ReferenceEquals(null, other))

            return false;

        if (ReferenceEquals(this, other))

            return true;

        return (int)Type == (int)other.Type;

    }

​

    public override bool Equals(object obj)

    {

        if (ReferenceEquals(null, obj))

            return false;

        if (ReferenceEquals(this, obj))

            return true;

        if (obj.GetType() != this.GetType())

            return false;

        return Equals((Cloud)obj);

    }

​

    public override int GetHashCode()

    {

        return (int)Type;

    }

}

​

class Program

{

    //Generic implementation of the binary search algorithm using a recursive approach

    static int RecursiveBinarySearch<T>(T[] array, T target, int? mostLeftIndex = null, int? mostRightIndex = null)

        where T : IComparable<T>, IEquatable<T>

    {

        //Initialize the state of the indexes that correspond to the first and last available indexes in the array or sub-array.

        if (!mostLeftIndex.HasValue)

            mostLeftIndex = 0;

        if (!mostRightIndex.HasValue)

            mostRightIndex = array.Length - 1;

        //If one of the indexes is in a situation like 0 < -1 or n < (n - 1) that means

        //the array does not contain the target value

        if (mostRightIndex < mostLeftIndex)

            return -1;

        //Get the middle position of the array

        var middleIndex = (int)(mostLeftIndex + (mostRightIndex - mostLeftIndex) / 2);

        //Test if the middle element is the target value (best case scenario)

        if (array[middleIndex].CompareTo(target) == 0)

        {

            return middleIndex;

        }

​

        //Is our target to the right or to the left of the current element

        return target.CompareTo(array[middleIndex]) < 0 //The target is smaller than the current element, then the target value must be on the left

 ? RecursiveBinarySearch(array, target, mostLeftIndex, middleIndex - 1) //The target value is bigger than the current element, then the target value must be on the right

 : RecursiveBinarySearch(array, target, middleIndex + 1, mostRightIndex);

    }

​

    static void Main(string[] args)

    {

        //An array of clouds...

        var sortedArray = new Cloud[]{new Cloud(Cloud.CloudType.Level10), new Cloud(Cloud.CloudType.Level20), new Cloud(Cloud.CloudType.Level30), new Cloud(Cloud.CloudType.Level40), new Cloud(Cloud.CloudType.Level50), new Cloud(Cloud.CloudType.Level60), new Cloud(Cloud.CloudType.Level70), new Cloud(Cloud.CloudType.Level80), new Cloud(Cloud.CloudType.Level90), new Cloud(Cloud.CloudType.Level10), };

        //Find the position of the cloud of level 40 in the array-

        var position = RecursiveBinarySearch<Cloud>(sortedArray, new Cloud(Cloud.CloudType.Level40));

        Console.WriteLine($"There is a Level 40 cloud at position {position}.\n");

    }

}