using System.Collections.Generic;

​

public class Client

{

    public void Main()

    {

        Builder builder = new ConcreteBuilder();

        Director director = new Director(builder);

        director.Construct();

        Product product = builder.GetResult();

    }

}

public class Director

{

    Builder builder;

    public Director(Builder builder)

    {

        this.builder = builder;

    }

    public void Construct()

    {

        builder.BuildPartA();

        builder.BuildPartB();

        builder.BuildPartC();

    }

}

public abstract class Builder

{

    public abstract void BuildPartA();

    public abstract void BuildPartB();

    public abstract void BuildPartC();

    public abstract Product GetResult();

}

public class Product

{

    List<object> parts = new List<object>();

    public void Add(string part)

    {

        parts.Add(part);

    }

}

public class ConcreteBuilder : Builder

{

    Product product = new Product();

    public override void BuildPartA()

    {

        product.Add("Part A");

    }

    public override void BuildPartB()

    {

        product.Add("Part B");

    }

    public override void BuildPartC()

    {

        product.Add("Part C");

    }

    public override Product GetResult()

    {

        return product;

    }

}