// GoF: Interpreter

using System;

using System.Collections.Generic;

​

// Context

public class RomanContext

{

    public int Input { get; set; }

    public string Output { get; set;}

    public RomanContext(int input)

    {

        Input = input;

    }

}

​

// Abstract Expression

public interface RomanExpression

{

    void Interpret(RomanContext context);

}

​

// Terminal Expression

public class RomanOneExpression: RomanExpression

{

    public void Interpret(RomanContext context)

    {

        while(context.Input - 9 >= 0) 

        {

            context.Output += "IX";

            context.Input -= 9;

        }

        while(context.Input - 5 >= 0) 

        {

            context.Output += "V";

            context.Input -= 5;

        }

        while(context.Input - 4 >= 0) 

        {

            context.Output += "IV";

            context.Input -= 4;

        }       

        while(context.Input - 1 >= 0) 

        {

            context.Output += "I";

            context.Input -= 1;

        }       

    }

}

​

// Terminal Expression

public class RomanTenExpression: RomanExpression

{

    public void Interpret(RomanContext context)

    {

        while(context.Input - 90 >= 0) 

        {

            context.Output += "XC";

            context.Input -= 90;

        }

        while(context.Input - 50 >= 0) 

        {

            context.Output += "L";

            context.Input -= 50;

        }

        while(context.Input - 40 >= 0) 

        {

            context.Output += "XL";

            context.Input -= 40;

        }       

        while(context.Input - 10 >= 0) 

        {

            context.Output += "X";

            context.Input -= 10;

        }       

    }

}

​

// Terminal Expression

public class RomanHundredExpression: RomanExpression

{

    public void Interpret(RomanContext context)

    {

        while(context.Input - 900 >= 0) 

        {

            context.Output += "CM";

            context.Input -= 900;

        }

        while(context.Input - 500 >= 0) 

        {

            context.Output += "D";

            context.Input -= 500;

        }

        while(context.Input - 400 >= 0) 

        {

            context.Output += "CD";

            context.Input -= 400;

        }       

        while(context.Input - 100 >= 0) 

        {

            context.Output += "C";

            context.Input -= 100;

        }       

    }

}

public class Program

{

    public static void Main()

    {

        List<RomanExpression> expressions = new() 

        {

            new RomanHundredExpression(),

            new RomanTenExpression(),

            new RomanOneExpression()

        };

        int input = 5;

        var context = new RomanContext(input);

        foreach(var expression in expressions)

        {

            expression.Interpret(context);

        }

        Console.WriteLine($"Roman representation for {input} is {context.Output}");

        input = 53;

        context = new RomanContext(input);

        foreach(var expression in expressions)

        {

            expression.Interpret(context);

        }

        Console.WriteLine($"Roman representation for {input} is {context.Output}");

        input = 789;

        context = new RomanContext(input);

        foreach(var expression in expressions)

        {

            expression.Interpret(context);

        }

        Console.WriteLine($"Roman representation for {input} is {context.Output}");     

    }

}