Chain of Responsibility: The chain of responsibility pattern is a way of communicating between 

objects.

class Program
    {
        static void Main(string[] args)
        {
            Approver director = new Director();
            Approver vicePresident = new VicePresident();
            Approver president = new President();

            director.SetSuccessor(vicePresident);
            vicePresident.SetSuccessor(president);

            Purchase p=new Purchase(1,200.00,"Assets");
            director.ProcessRequest(p);
            p = new Purchase(2, 1010.00, "Assets2");
            director.ProcessRequest(p);
            p = new Purchase(1, 2010.00, "Assets3");
            director.ProcessRequest(p);

            Console.ReadKey();
        }
    }

    abstract class Approver
    {
        protected Approver successor;
        public void SetSuccessor(Approver successsor)
        {
            this.successor = successsor;
        }
        public abstract void ProcessRequest(Purchase purchase);
    }
    class Director : Approver
    {
        public override void ProcessRequest(Purchase purchase)
        {
            if (purchase.Amount < 1000)
                Console.WriteLine("{0} Approved Request# {1}", this.GetType().Name, purchase.Amount);
            else if (successor != null)
                successor.ProcessRequest(purchase);
        }
    }
    class VicePresident : Approver
    {
        public override void ProcessRequest(Purchase purchase)
        {
            if (purchase.Amount < 2000)
                Console.WriteLine("{0} Approved Request# {1}", this.GetType().Name, purchase.Amount);
            else if (successor != null)
                successor.ProcessRequest(purchase);
        }
    }
    class President : Approver
    {
        public override void ProcessRequest(Purchase purchase)
        {
            if (purchase.Amount >= 2000)
                Console.WriteLine("{0} Approved Request# {1}", this.GetType().Name, purchase.Amount);
            else if (successor != null)
                successor.ProcessRequest(purchase);
        }
    }


    //Purchase
    class Purchase
    {
        private int _number;
        private double _amount;
        private string _purpose;

        public Purchase(int number, double amount, string purpose)
        {
            this._number = number;
            this._amount = amount;
            this._purpose = purpose;
        }

        public int Number
        {
            get { return _number; }
            set { _number = value; }
        }

        public double Amount
        {
            get { return _amount; }
            set { _amount = value; }
        }
        public string  Purpose
        {
            get { return _purpose; }
            set { _purpose = value; }
        }

    }