using System;

using System.Collections.Generic;

using System.Diagnostics;

​

public class Program

{

    public static void Main()

    {

        for (int i = 0; i < 100; i++)

        {

            Test();

        }

    }

​

    private static void Test()

    {

        var commonObject = new RandomObject()

        {Name = "Common", Weight = 60};

        var rareObject = new RandomObject()

        {Name = "Rare", Weight = 10};

        var LegendaryObject = new RandomObject()

        {Name = "Legendary", Weight = 5};

        var randomPool = new List<RandomObject>()

        {commonObject, rareObject, LegendaryObject};

        var randomPicker = new RandomPicker(randomPool);

        var pickedObject = randomPicker.PickRandomObject();

        Debug.Assert(pickedObject != null);

​

        Console.WriteLine(pickedObject.Name);

    }

}

​

public class RandomPicker

{

    private List<RandomObject> objectPool = new List<RandomObject>();

    public RandomPicker(List<RandomObject> objectPool)

    {

        this.objectPool = objectPool;

    }

​

    public RandomObject PickRandomObject()

    {

        RandomObject result = null;

        var overalWeight = 0;

        var offset = 0;

        foreach (var obj in objectPool)

        {

            overalWeight += obj.Weight;

        }

​

        var roll = Rngesus.rng.Next(0, overalWeight);

        foreach (var obj in objectPool)

        {

            if (roll < obj.Weight + offset)

            {

                return obj;

            }

            else

            {

                offset += obj.Weight;

            }

        }

​

        return result;

    }

}

​

public class RandomObject

{

    public string Name

    {

        get;

        set;

    }

​

    public int Weight

    {

        get;

        set;

    }

}

​

public static class Rngesus

{

    public static Random rng = new Random();

}