TheAirline.Models.Airlines.Airline.GetFlightCodes C# (CSharp) Method

        public List<string> GetFlightCodes()
        {
            var codes = new List<string>();

            IEnumerable<string> rCodes =
                Routes.SelectMany(r => r.TimeTable.Entries).Select(e => e.Destination.FlightCode).Distinct().ToList();

            for (int i = 0; i < 1000; i++)
            {
                string code = $"{Profile.IATACode}{i:0000}";

                if (!rCodes.Contains(code))
                {
                    codes.Add(code);
                }
            }

            return codes;

            /*
            var routes = new List<Route>(this.Routes);

            var entries = new List<RouteTimeTableEntry>(routes.SelectMany(r => r.TimeTable.Entries));

            foreach (RouteTimeTableEntry entry in entries)
            {
                if (codes.Contains(entry.Destination.FlightCode))
                    codes.Remove(entry.Destination.FlightCode);

            }

            codes.Sort(delegate(string s1, string s2) { return s1.CompareTo(s2); });

            return codes;
             */
        }