using System;

using System.Collections.Generic;   

using System.Linq;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Hello World");

        var airs = new List<Air>();

        airs.Add(new Air(){ OriginAirportCode ="AU", DestinationAirportCode = "AU"  });

        airs.Add(new Air(){ OriginAirportCode ="AU", DestinationAirportCode = "NZ"  });

        var p = new Purchase(){

            Id = 1,

            Air = airs

        };

        Console.WriteLine("isOneway: {0}", isOneWayFaring(p));

    }

    private static bool isOneWayFaring(Purchase p)

    {       

            var originCountryCode = p.Air.FirstOrDefault().OriginAirportCode;

            var destinationCountryCode = p.Air.FirstOrDefault().DestinationAirportCode;

​

            foreach (var air in p.Air)

            {

                if (!(air.OriginAirportCode.Equals(WebConstants.AustraliaCountryCode)

                    || air.OriginAirportCode.Equals(WebConstants.NewzealandCountryCode)))

                    return false;

                if (!(air.DestinationAirportCode.Equals(WebConstants.AustraliaCountryCode)

                    || air.DestinationAirportCode.Equals(WebConstants.NewzealandCountryCode)))

                    return false;

​

            }

            return true;

        }

}

​

public class Purchase

{

    public int Id  {get; set;}

    public List<Air> Air {get; set;}

}

public sealed class WebConstants

{

        public static string AustraliaCountryCode = "AU";

        public static string NewzealandCountryCode = "NZ";

}

public class Air

{

    public int Id  {get; set;}

    public string OriginAirportCode{get; set;}

    public string DestinationAirportCode{get; set;}

}