C#-Code

using System;
using System.Collections.Generic;
using System.Linq;

namespace Zoo
{
    public class Zoo
    {
        private static AnimalFactory animalFactory;
        public static List<IAnimal> AnimalsInZoo = new List<IAnimal>();

        private static void Main()
        {
            animalFactory = new AnimalFactory();
            
            AddRandomAnimals(200);
            Console.WriteLine("Random Animal Factory");
            PrintZoo();

            AddBalancedAnimals(200);
            Console.WriteLine("Balanced Animal Factory");
            PrintZoo();
        }

        private static void AddRandomAnimals(int numberOfAnimals)
        {
            AnimalsInZoo.Clear();
            for (var i = 0; i < numberOfAnimals; i++)
            {
                AnimalsInZoo.Add(animalFactory.CreateRandomAnimal());
            }
        }

        private static void AddBalancedAnimals(int numberOfAnimals)
        {
            AnimalsInZoo.Clear();
            for (var i = 0; i < numberOfAnimals; i++)
            {
                AnimalsInZoo.Add(animalFactory.CreateBalancedAnimal());
            }
        }

        private static void PrintZoo()
        {
            var animalTypeList = AnimalsInZoo.Select(x => x.GetType()).Distinct();
            foreach (var animalType in animalTypeList)
            {
                var sum = AnimalsInZoo.Count(animal => animal.GetType() == animalType);
                Console.WriteLine(sum + " - " + animalType.Name);
            }
        }
    }


    public class AnimalFactory
    {
        private readonly List<Type> animalTypes;
        private Type lastAnimal;
        private Type secondLastAnimal;

        public AnimalFactory()
        {
            var availableAnimalTypes = new List<IAnimal>
            {
                new Crocodile(),
                new Lion(),
                new Penguin(),
                new Snake()
            };
            animalTypes = availableAnimalTypes.Select(animalType => animalType.GetType()).ToList();
        }

        public IAnimal CreateRandomAnimal()
        {
            var random = new Random();
            var index = random.Next(animalTypes.Count);
            var animalClass = animalTypes[index];
            return (IAnimal) Activator.CreateInstance(animalClass);
        }

        public IAnimal CreateBalancedAnimal()
        {
            var random = new Random();
            var animalListReduced = new List<Type>(animalTypes);

            animalListReduced.Remove(lastAnimal);
            animalListReduced.Remove(secondLastAnimal);

            var index = random.Next(animalListReduced.Count);
            var animalClass = animalListReduced[index];
            secondLastAnimal = lastAnimal;
            lastAnimal = animalClass;

            return (IAnimal)Activator.CreateInstance(animalClass);
        }
    }

    public interface IAnimal    {}
	
    public class Lion : IAnimal    {}
	
	public class Penguin : IAnimal	{}
	
	public class Snake : IAnimal	{}
	
	public class Crocodile : IAnimal	{}

}