using System;

​

public class Program

{

    public static void Main()

    {

        Context context;

        // Three contexts following different strategies

        context = new Context(new ConcreteStrategyA());

        context.ContextInterface();

        context = new Context(new ConcreteStrategyB());

        context.ContextInterface();

        context = new Context(new ConcreteStrategyC());

        context.ContextInterface();

    }

}

​

/// <summary>

/// The 'Strategy' abstract class

/// </summary>

abstract class Strategy

{

    public abstract void AlgorithmInterface();

}

​

/// <summary>

/// A 'ConcreteStrategy' class

/// </summary>

class ConcreteStrategyA : Strategy

{

    public override void AlgorithmInterface()

    {

        Console.WriteLine("Called ConcreteStrategyA.AlgorithmInterface()");

    }

}

​

/// <summary>

/// A 'ConcreteStrategy' class

/// </summary>

class ConcreteStrategyB : Strategy

{

    public override void AlgorithmInterface()

    {

        Console.WriteLine("Called ConcreteStrategyB.AlgorithmInterface()");

    }

}

​

/// <summary>

/// A 'ConcreteStrategy' class

/// </summary>

class ConcreteStrategyC : Strategy

{

    public override void AlgorithmInterface()

    {

        Console.WriteLine("Called ConcreteStrategyC.AlgorithmInterface()");

    }

}

​

/// <summary>

/// The 'Context' class

/// </summary>

class Context

{

    private Strategy _strategy;

    // Constructor

    public Context(Strategy strategy)

    {

        this._strategy = strategy;

    }

​

    public void ContextInterface()

    {

        _strategy.AlgorithmInterface();

    }

}